I have this seat, but in princess. My DD is 3. She should be able to use it until 8 or 9. I love it. It is much lower profile than the other seats with a 5 point harness, so she she can get and out of the car on her own (I just have to buckle), but it is huge not to have to lift her.). She loves it too. I can fit 3 seats across, even in my smallish car too. It is metal, not plastic.
Re: Car Seat Question?
I don't know anything about the one you have linked, but I do have the Nautilus and I love it (so does DS).