Can anyone comment on the accuracy of Orion Telescopes clock
drived for their EQ series (1 or 2, in particular) tripods?

The drives I am refering to, are EQ-1m, EQ-2m, etc.

I will be using it for 35mm long term (up to an hour) exposures,
with lenses up to 500mm in size.

Thanks,
-Robb