Re: Another 3 Across Post :)
The problem with the Harmony Defender 360 is that it has a VERY short crotch strap. I would have bought it for my 5 year old if it weren't for that. From all the pics I've seen, there is no way she would fit in it without it being very uncomfortable.
We ended up getting my 5 year old a Radian R100 because we needed a narrow seat for a 3 across in a Jetta. I really like it. We have a Radian XTSL (Sunshine Kids version with head wings), but I passed that on to my 2.5 year old. If you are going for a Radian, I'd go for one without the head wings for a 5 year old because the head wings get in the way once the child nears the top slots.