We have the Kompressor. I turned DD2 at 20months recently. Her legs were just too long for her to be comfy (I have 3across the back seat so her legs dangling over the sides wasn't an option with her in the middle). She is seriously off-the-charts tall too. She could still be rear facing if she was the only kid in the back seat.
On the downside they really sit upright when rear facing. And the tether makes it a pita to get them in and out.
I really love the seat though as our original baby seat, my DD1 was too tall for at 2! So I should get lots of use out of this one.