Which 5-pt harness booster--Britax Frontier 85 SICT vs. Diono Radian RXT/R120?

[goldenpig]

I need help with figuring out what our next car seat purchase should be. Right now we are using six car seats in three cars (me, DH and nanny all do various pick ups and drop offs regularly, so I prefer to keep car seats installed) but DD is reaching the limits of one of hers (Diplomat) and I am thinking of getting a booster, but I would like a 5-pt harnessed booster and don't know which one to get. We have been doing extended rear-facing--DD was rear facing until age 4 and DS is still rear facing at 2.5. I have been reading about the benefits of extended harnessing at sites like this one: http://www.kyledavidmiller.org/car-seat-safety-5-point-harness-is-safest.html and I would like to keep her harnessed as long as possible.

Both of them are peanuts--5 yo DD is 39.5 inches and 34 lb and 2.5 yo DS is about 34 inches and about 27 lb, so height and weight limits are not usually an issue for us. But I'm not sure what the best strategy is since we will have another baby coming and trying to figure out the best long-term solution.

Currently we have the following carseats:
1 Graco Snugride (the original 22 lb version)--manufactured 5/3/07 and has a stamp in the plastic saying "Do not use past 12/2013". I am confused--I thought they expire after 6 years, so does it expire May 2013 or Dec 2013? Baby is due in March 2013 so I'm wondering if I can use this for only 2 months, or 9 months which would make it a more viable option. We have 3 car seat bases so we can move the seat from car to car.
2 Britax Diplomats (I need to check the expiration dates on these, but I bought them around when DD turned 1 so I assume these will last till the baby is about 18 months)
2 First Years True Fit Premiers (with the anti-rebound bar)
1 Britax Advocate CS (the original)
1 Graco Nautilus

Current setup:
Me-2012 Odyssey:
DS RF in TFP behind driver
DD FF in TFP behind passenger
DH-2001 Lexus RX300 5-seater SUV (LATCH only outboard, not in center)
DS and DD both FF in Diplomat (DH takes DD to school every morning but DS almost never rides in DH's car)
Nanny-1998 Corolla (no LATCH, no tethers and I am nervous because she takes out the car seats every weekend and I don't trust her to do a tight install)
DD FF in Nautilus behind driver
DS RF in Advocate behind passenger

We are hoping to find some sort of used (or less expensive new) minivan for the nanny so we can leave the car seats installed. DH nixed the idea of her driving our new minivan and plus when I'm on call or working late I sometimes get home after the nanny leaves, so trading cars with her isn't really an option. Otherwise DH could get a new car and give the nanny the RX, but he isn't really interested in a new car right now (he's very picky).

So I am thinking of either getting a Britax Frontier 85 (I'd like to get the SICT version if it fits as I'm a bit of a SIP nut--I have that huge Advocate), or DH suggested a Radian because he's worried about doing 3 across. Apparently they are no longer called Sunshine Kids and are now Diono Radian RXT or R120 (not sure about the differences between these two models). He thinks it will be easier to fit 3 across since it's narrower. And it does work rear-facing unlike the Frontier so we could potentially use it for the baby, but apparently it's so tall it's hard to install rear-facing. DD occasionally carpools or does playdates with other families so I'd like whatever we get to be easy for other moms to install (I feel like more moms are familiar with Britax). Plus the Frontier works without a tether and will last longer since it turns into a convertible booster.

So which should we get--two Britax or two Dionos? Or one of each? Or something else entirely (like another convertible for the baby)?

This is the setup I'm thinking of for 3 across--would this work? I could also put a kid or two in the back of the minivan if needed if 3 across doesn't work.
My Odyssey-baby in Snugride first then RF Diplomat behind driver, DD in middle in Frontier SICT/Radian, DS RF in TFP behind passenger
DH's RX300- DS in RF TFP behind driver, baby in Snugride then RF Diplomat in middle (since he and the baby will rarely ride in this car), and DD in Nautilus behind passenger for ease of access since she rides in this car daily.
Nanny's Corolla (or hopefully minivan soon)-DD in Frontier/Radian behind driver, baby in Snugride then ?move into the RF Advocate when it expires, DS RF in Advocate then maybe ?move into a third 5-pt booster down the line.

I feel like this is one of those math/logic puzzles that I can't quite figure out! Any advice would be super appreciated from all you car seat gurus!

[legaleagle]

So you'd like a seat combo that includes a seat on the plus 1 seat? I know the carseatblog.com review of the oddy listed some seats that work well on the plus 1.

For DH, you will likely need at least one radian because they are so narrow. Also, they puzzle well with britax seats, which is useful since you have 3 already. There's also the clek foonf which is coming out this fall that is very narrow but also $450+, and the combi coccoro, which is a tiny, narrow seat, but should last your peanuts plenty of time.

[goldenpig]

Thanks, legaleagle--I checked out the review you listed with the best car seats for the middle seat. I decided to get a Frontier 85 SICT. I want to keep her harnessed as long as possible and I love my other Britaxes. I read about the Foonf, but I think I'll wait till it's out to see how the reviews are. And the LATCH issues with the Radian made me nervous. I did buy a Coccoro once, but returned it because I just couldn't get a good secure install with the rounded base (got True Fit Premieres instead). I'm just buying one Frontier for now and will re-evaluate when the baby comes to see if we need any additional ones. Actually we also ended up getting another minivan. So the car seats don't have to be so narrow. Thanks!

[KrisM]

Graco seats all expire in Dec. of the 6th year, so you do have until the end of 2013 for the infant seat.

[Simon]

I can't answer all your questions because my brain is a little too fuzzy for that much thinking this early in the morning.

Afaik, a Frontier is too wide to fit 3 across in all but the biggest of backseats so I would not count on it working anywhere but a minivan. Radian is probably a must for the 3 across situations.

You are correct that a Britax is an easier install, but the Frontier is a pretty darn big seat and won't necessarily fit in friends' cars for playdates. If you think that is going to be a (more) frequent event, I'd look seriously at the Maestro as a narrower combo seat. Its not a great booster, but you can easily hand it down and pick up a good dedicated booster when she's ready.

The narrowest infant seat is the Graco 30.

Have you tried out any of those combos in the actual car? Sometimes seats puzzle well together, but you're talking about some pretty wide seats (Diplomat, TFP) and I'm not sure they'll fit.

I just wanted to say that we really like having Ds1 and Ds2 (who are close to the ages of your 1st two Dc) together in the back seat/3rd row and have Ds3 in the middle. This probably won't work if your Dc don't get along, but Ds1 is great about helping Ds2 with things like snacks or dropped toys and we have easy access by just flipping down one of the middle row seats and can easily reach in to buckle Ds2. Ds1 can buckle himself in.
So our set up is:
Ds1 driver side 3rd row, baby rf driver side middle.
Ds2 3rd row pass. side.

The real bonus is we can use any seats we want because we aren't trying for the 3-across back there and its easy to add a friend's seat to the middle row without having to un-/re-install our own seats before and after.