I don't have the Cubicle Premium one, but from reviews it seems people like it. It's obviously a matter of preference, of course.
Concerning the stickers, though, no, the centers won't accept square stickers very well. The cap is rounded and the flat portion is circular. You might try using original 356 center caps with it, since those were flat and the 356 is very similar to the Air, but I can't tell you for sure if they fit and you might get a lot more catching.
It's funny, I actually really like the circular centers. I can't say why, I just do...