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I do not have a problem with any kind of slippage, but on the other hand, all depends on what you want out of the system.
For up to one hour of tracking and visual, there are no problems. System accepts commands from guider, so that should correct the possible problem 100%.
Since I do not have permanently mounted telescope, whenever I use it I just level it and then point to a known star and reset its coordinates, this is good enough for majority of my purposes at the moment.
For GOTO I had some problems in the past with slippage in the azimuth butthis was because of the design specifics (I am using a roller reduction and at the beginning there was not enough pressure in one direction. I believe I sorted this out with different design approach.
I never noticed any problems on altitude axis, where the telescope rides on the axis with its full weight.
BTW, I know for sure that many professional instruments are using friction roller reduction, it is cheap and there are no periodic error, inherent to gears.
Encoders should correct for slippage, however this will depend on their resolution.. and this is an area where I have some problems (oveshooting when telescope is returning to the correct position when encoders indicate the slippage, and that problem seems to be specific to my system only, since nobody in the bartels community knows what is the cause and cure).
Nevertheless, I am using encoders only as an input to a new position, when I want to observe something on the other direction during starparties (without encoders, I should either slew to the new position with motors which takes a long time - or I should stop tracking, then point to the new object, then I find that object in the data base, then reset to the new coordinates - all this takes a long time as well).
The easiest way to hop to a new object is the same as with conventional dobson: just stop tracking, push the scope to a new direction (encoders are updated every second automatically) and when there, start tracking again. GOTO function I am using for close objects within couple of degrees, and only when I am looking for them because I do not know exactly where they are.
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