Like Tilly - I also have the SPC adjustable rear camber arms. I am not sure what springs Tilly has, but I swapped out for the MS3 springs. They are okay. Ride height is good - not too harsh or soft, but much improved over stock. Sometimes the rear looks a little low.
Far as the rear camber arms. If I did it over again, I would get the MazdaSpeed RCA's. They are not adjustable, but really - who needs to adjust the rear camber? Nothing is wrong with my SPC's, but they were a pain to install and the adjustment is also a PITA.
michael.