Booster too big for child?

[sarsah]

I let DS (will turn 5 in three weeks) ride in his brother's Compass B510 today in DH's car today and the Compass just seems so HUGE for him. He not tiny by any means -- tall and thin (43 lbs) with a long (16") torso. The booster seemed to adjust the seatbelt properly on him, but his knees bend before the edge of the seat. He sat up correctly today, but I'm wondering if I need to wait until he grows more to let him ride in the Compass again. His main seat is a Britax Marathon, but he's almost too tall for it and I'm choosing to move him to a booster once he is too tall (yes, I know there are 5-pt harness options -- Nautalis, Regent, etc., after the Marathon, but I'm choosing to move him to a booster for various reasons).

So, my question is -- How do I tell if a booster seat is too big for a child?

thanks,
Sarah

[joolsplus3]

That IS a pretty big seat (it's not my fault you own it, is it? :rolleyes:)...I almost wish some bigger seated boosters had higher weight and age limits... The problem is that he may scootch forward so that his knees can bend and legs dangle more comfortably, and that might cause the lapbelt to be up too high on his abdomen in a crash, which is obviously what boosters are supposed to be preventing in the first place. I really like the Parkway for littler kiddos, and the Turbo is shallower than the B510 too, even the Vivo or Vivo Lite are shallower and better for littler kids.

[sarsah]

The Compass has been a great seat for my oldest DS -- I just wish it was taller because he's almost outgrown it in height. I have a Monterey on order (intended for my youngest), but was thinking of putting my oldest in it (since it's taller than the Compass) and putting my youngest in the Compass. My youngest did fit very well in the Parkway, but the head wings were too close together to work with wireless headphones (for the DVD player). He hates riding in the car, so we 'need' the DVD player for everyone's sanity.