My son is about to outgrow his Britax Roundabout and we are debating b/t the Britax Frontier and the Graco Nautilus. He's 5 y/o and only 27lbs, 41". Rather than buying two more seats, I'd like to just buy one and that's why we are considering these two seats.

The only complaint I've heard about the Nautlius is with the distance of the crotch strap. We checked out both seats yesterday at the store and the salesman said the Frontier does not have the ablity to be a backless booster.

So I've got one con for each seat and I'm wondering if anyone can comment on these two issues. Does the fact that the Frontier not convert to a backless booster present any issues? I'm just thinking my son will be going to highschool and still in a booster seat (just kidding) Shallow but thinking of his self esteem, obviously safety is the top priority and he'll be in a 5pt harness for as long as I can keep him there.

Thanks so much!