A.W.
I know how confusing and frustrating car seat decisions can be. It's actually a topic that is really important to me. I found a great resource that I like to share with people trying to make decisions on what to buy. I know I recommended the Graco Nautalis yesterday (everyone that I know that has this seat loves it because it has the three different uses and provides the 5 pt. harness option up to 65 lbs.). Another one to consider is the Safety First Apex 65. You can use the 5 pt. harness on this seat up to 65 lbs. and then it also converts to a high back booster. Here is in on Overstock at a great price:
http://www.overstock.com/Baby/Safety-1st-Apex-65-Booster-...
Here is the other resource I have learned a lot from.
http://www.kyledavidmiller.org/pages/828/About_Us.htm
If you have a chance, read the family's story and watch the video about their son. Like I said, it is very informative.
Hope you don't mind me sending this info along! I just know how much it helped me!