I have had a Betstco medium duty 175 for about 2 years. Initially, they shipped the unit with a fill plug vs. a vent plug. I would agree the documentation leaves a lot to be desired. As an example they show in 2 places the gearbox takes either 1 qt or 3 qt of oil; neither of which is right since if you attempt to put in 1 qt it overflows (don't ask how I know LOL). Also, it describes how grease fitting can take a lot of grease... Finally, my copy of doc showed my mower was to take 3 belts (which is inaccurate).
Assembling was not an issue, the doc was adequate; but not great. Some things to look out for, make sure the swellable sleeves allen screw are tight, they come already on the shafts; but the screws may need tightened, same with the belts. Check the shear bolt to make sure it is tight, mine was loose after period of time.
I recently started to feel a vibration and mower getting very loud. I tried swapping the pto shaft, still there so I had support ship me the bladeshaft bearings (in fact they shipped the bearings in the flanges); but their QA was not good as the seal they sent was not right size.
The bearings/flanges took care of the issue.
Overall, for the price I paid ~1,300 I can't complain as their support has actually been very responsive and good to work with. I mow ~25 acres with it at most twice a year and pasture edges every other week during summer.
I have heard they are changing manufacturers, so you are looking at them you might ask them.