Wow, that's very good to know--thanks! Will definitely check out BRU's offerings and see about trading in our old clunker.
As for the Radian, dd is pretty small also (she'll be 4 in March and is about 33lbs and maybe 36" or so?), and she hasn't ever complained about being "low" in her carseat. Talk them into letting you try it out in your car before you decide whether to buy one or not. (Do they even sell Radians at BRU? I think we had to buy ours on amazon, but that was way back in 2008...)
They sell the Radian on their website, but the trade in is store only. I emailed customer service and am waiting to find out. Their HQ is near my parents' so if it's in any store, it would be in that one!