We recently moved my 3.5 yo daughter to a Graco Nautilus when she was too tall for the Roundabout (she's about 35 lbs and 36"). She LOVES the Nautilus, especially the cup holder. I chose it because she can stay in a 5-point harness for longer than in any other seat, which is much safer. I had originally bought the Britax Frontier, but our local police officer who was installing it said they have had a lot of installation difficulties with the Frontier and recommended the Nautilus instead (it's also much cheaper). My 1 yo son is now in the Roundabout, and I'm still very happy with it. We also have a Britax Boulevard (for my 3.5 yo), and I find the Roundabout easier to use than the Boulevard. I don't know about the newer version of the Roundabout, but if your old one is less than 5 years old and still in good shape (and, of course, never been in an accident), it sounds like you could probably use that rear-facing for your daughter.