I just wanted to also add, that if your dd is just outgrowing her roundabout now and it's by weight and not height, then you're really not likely to actually need the height of the Regent and would probably be fine with an apex, radian, or high weight britax convertible, even the triumph advance or the fisher price safe voyage deluxe. The top harness height on all of those are 2 to 3" higher than on the roundabout, and at 4yrs old that's likely to be least another 2 or 3yrs of growing room.
If you're planning to keep her harnessed as absolutely long as possible, no matter her age, then the regent probably is your best bet. But if one of those other seats will get you to 6 or 7yrs old, I don't see the need to spend the money on the regent. :twocents:
The best seat is one that fits your child, fits your vehicle, and will be used correctly every time. Britax is often recommended because of the higher weight limits, and in the case of the convertible seats the built in lock-offs. They're not necessarily the "best" or "safest" though. We have no way of knowing that.
I would seriously consider the apex 65 or else the Radian (65 or 80, only difference is in weight limit & covers/cushions,) along with the new true fit when it comes out since they're all low profile seats and older kids tend to like the lower profile because they seem like less of a baby seat.
I also just wanted to add, that a seat is outgrown ff'ing when any one of the following happen:
- weight limit is reached
- tips of ears reach the top of the seat shell
- shoulders go over the top harness slots (measure at the shell by poking your finger through the cover since covers often slide up or down.)
Assuming that the roundabout hasn't been outgrown by height, I just really don't see the extra height of the regent being needed - the top slots on it are 4.5" higher than the roundabout, and that much growing room at 4yrs old seems a bit like overkill to me. :twocents:
FWIW, and just to give a comparison, my dd is over the 2nd from top slots on the MA at almost 3.5yrs old and they're .25" taller than the RA. She still has 3" growing room before her shoulders are even with the top slots in the Radian. Based on her growth curve though, I fully expect her to make it to 5yrs old in the MA and probably age 6 in the Radian. Being as your dd is already older and not quite as tall in the torso, I'd expect your dd to get to an even older age in any of the higher weight seats available.