I have used several motors. DigiPower SG-2100, Moteck SG-2100, PowerTech DG-280/B and PowerTech DG-380.
When comparing these models, I find that they are all VERY reliable. The SG-2100's and the DG-XXX series are equally compatible to USALS and DiSEqC 1.2 control.
I did have an issue with one of the older SG-2100 motors as it would not handle the weight of a 1M Winegard dish. It could pan east or west of zero, but had a very difficult time panning back when gravity was working against it. This was only one of the SG-2100 motors and I cannot recall if it was a Moteck or a DigiPower version. All other SG-2100 motors that I have do not seem to have this problem, although I have not used them in quite a while as I have since been using the DG-280 and DG-380 motors.
Walrus may have been able to get an SG-2100 to move his 1.2 M dish, but I would be apprehensive to recommend the SG-2100 motor for this size of dish. I believe it would be borderline in spec's. That doesn't mean that it won't work, but that it might be working harder and have a shorter lifespan with such an application.
My personal opinion is that the DG-280 and DG-380 series motors are much more worthy of the initial expense. The SG-2100 motors are highly reliable and less expensive, but I find the price difference negligable.
I do not intend to rob the DG-XXX series motors of their status, but I must provide information accurately. Two of the SG-380 motors that I tested did not have the four housing bolts completely tightened. I did not observe this intially, but while I was trying to set up the motorized dish, I ran into problems with the arc that left me scratching my head. When I got to examining the motor, I noticed that the upper and lower housings (or shells) were separating from eachother.
The dish was attached to the motor tube and hence to the lower housing. The upper housing is fixed to the motor bracket. Because of the gap between the two shells of the housing, my latitude or motor elevation developed an error and would not track the arc.
Once these four bolts were securely tightened, the problem was corrected, so there was no malfunction with the motor itself. I beleive that the assembly technician was either working on these two motors on a Monday (possibly with a hangover) or on a Friday (and in a hurry to get home).
Both motors are assembled in the same fashion, so this could occur on either. You should check this before installation of any motor. This was not initially apparent, it only appeared after the weight of the dish assembly was applied.
I have not experienced nor duplicated the scenario that Walrus stated, so I do not have information on that issue. I have witnessed that the SG-2100 motor sometimes would not pick up or execute the move commands when changing sats when I had that motor set behind a SW21 and a DiSEqC switch (in series). I sometimes had to resend the move command more than once before it would move. i.e. select another satellite and then reselect the satellite that I wanted. This could have been the motor, the switch matrix that I was using or the receiver. I cannot confirm this as it was too infrequent of a problem to troubleshoot and isolate.
I would recommend either motor, but I prefer the DG-380 for the larger dishes like the 1.0 - 1.2 M. You won't go wrong with one of these motors, regardless of the dish size (as long as you stay within the recommended limits for any one of them).
RADAR