Yep it's the buckling that's the pain and why we kept him in the radian at this point. Well that and the fact that it fit! I wish he could stay in it longer, just for that reason. At this point I would be comfortable with him in a booster otherwise.
I was wondering about puzzling them together. My husband is the one who installs them (I have zero patience for it-and we get them checked) so I am actually kind of clueless about the fits. I just do the research.

My other boys are 5 years old and just about 3 years old. I would put my (45lb? ) 5yo boy in a booster if it puzzled in a better way. My almost 3 year old just went forward facing in his radian. We have a britax marathon we could potentially use again for him, ff'ing. We actually had that rear-facing in the middle and it fit *better* than the radian due to the puzzling, but he surpassed the rear-facing weight limit and then it wouldn't fit ffing. Maybe it would with the booster? I think my dh would die if I bought another carseat.
What do all the 3-across people do when the kids grow into a booster?
Thanks for your response. Also- do you happen to know if it's OK if his shoulders are at or very slightly above the top slot, if his ears are well below the top of the shell? I thought the head height trumped the other factors, but I'm not sure. He's 52 in. (limit 53 per manual). I tried to call Radian but haven't reached yet.
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