I made the Datsun 180B from the ground up too
I cannot comment on the pros and cons of the servo system
as I have no experience of it.
Feedback on Mel's site about the Servo system is very positive.
I couldn't add anything more about the stepper system except
maybe about positional feedback and stepper stalls during slews.
If the system has been designed and refined well, as Bojan refers
to in his post, the slews can ramp up in speed, slew at a linear
rate and ramp down....all without a stall or problem due to inertial
load. On my system the slew is about 2 degrees per second.
But I hardly ever use it...it's mainly push-to locally or a correction
using the ASCOM interface in microsteps.
Also, positional feedback can be made to be quite accurate.
And quite cheaply too. 4000+ count rotary encoders can be a few
hundred dollars each US.
Or you can rip apart a cheap serial mouse and use the photo
interrupters out of it. Your imagination is your only limitation as
to the practical implementation.
Here I recently upgraded my positional accuracy on the homemade
GEM to be 8500 counts per 360 degrees on DEC and 25,000 counts per 360
deg on the RA. All using cheap recycled bits and pieces.
FWIW
regards,
Steve