[bojan]

There is no rubber, just metal-to-metal (brass, steel, al.. with additional pressure in a form of springs holding wheels together... and there is no slippage. Or if there is, it doesn't matter enough to be noticed as a problem).
When it wears off sufficiently (big aluminium wheel, brass and steel will be OK), I will be long gone from this world :-) If not, I will machine the new one.
Tracking is as per Mel Bartels' : software running on 100MHz pentium, DOS, controlling both AZ and EL steppers appropriately.
It does slewing, Goto and tracking at sideral or lunar or solar rate.
It also understands LX200 protocol for autoguiding (but I do not use it, not yet).
I do not have field de-rotator yet (I am using this setup only for visual and occasionally for planetary photography), but Mel's software supports FR. Perhaps one day...
My focuser is easily detachable (Carl Zeiss style) and I am working now on focuser for camera at prime focus.
Mirror is mounted such that I have focus ~95mm outside the tube (my own design), and it will be OK with new camera focuser. I think even if field flattener id fitted, the focus is out enough.

For Moon and planetary photos (I tried couple of times, I saw that I can do it and that's it) I used projection, with camera (kyocera M400R or any other with 50mm filter thread) mounted on adapter (inside which was 9mm eyepiece)