I'm considering the Marathon for my 2 1/2 yr old (she's @31 lbs and 36 inches) because her baby sis needs her Roundabout. I'm just wondering if the crotch strap being closer to the back of the seat has been a problem for anyone. My mom thinks that once Abby's potty trained, the strap won't be so snug against her (no bulky diaper). If anyone has any input or comments, I'd really appreciate it. I'd hate to spend the $250 and then end up having a hassle everytime I put her in the seat!