I've been using an X-55 for about a year now, and I am very lucky to have no issues at all (no ghost button presses, mysterious joystick movements in game, etc.) All the buttons work fine, even the mouse nipple (which I have programmed as the mic switch).
It's still very sharp from the time I bought it so i'm very happy with it. I chose it over the Warthog because of cost. Bottom line is, I am very happy with the rhino even with the A-10C module :)