Car Seats

This is such an anxiety producer for me. I want my girls to be just as safe as I feel my son is in his Britax Regent and it's time for the girls to have new seats since they are 40 pounds. I have a STRONG belief that children should ride in a 5 point as long as possible so I began narrowing the seats down based on ability to harness longest. If we have another little one then the choice would be so simple... (to buy a Radian xtsl from the beginning) rear face them to 45 pounds! Right now my choices for the girls have been narrowed down to the Graco Nautilus and Britax Frontier 85. If I can wait for a good sale then the price difference of the Frontier 85 vs. the Nautilus would only be $140.00 (buying two remember). My main problem with the Nautilus is the crotch strap may not allow the girls to be harnessed as long as I need. The Frontier is a good choice for me if my son ends up needing a booster I could just switch the seats, giving his Regent to one of the girls and them still be safe.