I must have missed this post somehow. You will find that the Astromeccanica motors and belts totally get rid of any sudden micro 'jumps' due to the spur gears. These are far more annoying and unpredictable than any other tracking error. My HEQ5 (with Astromeccanica motors and belts) easily handles the TAL 200k for astro imaging up to twenty minutes at 1790mm (autoguided) and every image is fine!
Just like you I just picked up a EQ6 with belt drives and will use this for my 'home' mount and put the HEQ5 on the EQ6 tripod for a portable astrophotographic mount.
Bert
See here
http://www.iceinspace.com.au/forum/s...light=tal+200k