Opinions needed on Deep vs shallow side walls.

In an effort to have more room in the back seat for a passenger and two carseats (and eventually another child), I am pretty sure I want to get a Flora Radian for my DD. When my DS was a baby I had a Marathon which I liked but my kids have short torsos and long legs so he was really cramped in the leg area by 2 and he hit the weight limit at 2.5.

How's the fit in the Radian for a 19/20 lb baby? I'm pretty sure you cant use the headwings for a baby that small, but do they get in the way?

How concerned are you with the shallow side walls in regards to safety? I know that rearfacing is very protective for side impacts but I still worry for some reason.

I have tried a old style radian with the wider RFing foot in my car and it only fit behind the Driver, which is not a good place for it in our vehicle. I am thinking that with the narrower foot it will fit in all the positions and that would be great because it would be nice to have it in the middle sometimes.

Would you prefer to have a more protective seat? What do you like for a baby my DD's size?

I don't know why I am having such a hard time deciding on a seat for her... She has been in a hand-me-down(from her brother) Uptown since 4 months. This will be her first seat all for her so I really want to make the right decision.

My DD is 21 pounds, 30 inches, 18 months old. She has average proportions, and is on the third slots RFing (at the slots). The headwings fit her just fine. If you're not using the headwings, they don't get in the way, because they just sit at the top of the seat.

I have a TrueFit in one car and RadianXT in the other. Almost opposite ends of the spectum in terms of deep side walls. I have no problems with her riding in either seat.