car seat advice for lightweight 5 yo, please

[WaturMama]

My 5.5 yo ds is just over 40 lbs, so he has outgrown the one and only car seat he has had--the Britax Roundabout. He is average height, but a lanky little person. I'm getting stuck with the car seat question. I've googled extensively, but not finding a good overview and don't feel like I'm getting my mind around this. I'd appreciate some recommendations. We could do booster seat or 5 pt harness, and booster would be more convenient, but 5 pt, safer, correct? If that's the choice I'll go for safer.

Is there one more safe car seat that will last us until he no longer needs one? It seems the Radian is good for not taking too much space in a smallish car (we have a Honda CR-V). What about Britax v Radian and the myriad of Britax choices and is there something cheaper than is just as good?

Any answers or direction to a good web site would be greatly appreciated.

[pbjmama]

Try posting in family safety. It would help to know how tall he is too. We have the graco nautilis and really like it. Weight limit is 65 lbs. 

[ecoteat]

I was going to say the same thing--post in Family Safety, and also that we just got a Graco Nautilus for my 4.5 yo (33 pounds, 40 inches). She'll be able to use the harness for a long time, and then she can use it as a backless booster, then as just a booster seat. She LOVES it and it is the most sturdy and substantial seat we've ever used.

[WaturMama]

Thanks to you both. I'll head over to Family Safety.