The QJ pyraminx starts off very stiff, is decent for a short amount of time, then begins popping horribly. I've had my Mefferts Pyraminx II for over a year and it's still good.
Great!!! thanks. The only thing was that I reeeeeally like tiles, and the mefferts costs about four bucks more but for the consistency in being great over that long, it's definitely worth it.