well I'll do the math since it is pretty easy in this case.....

50A * 100V means the PP is a 5 Kilowatt unit at max, 1.7 KW at 20A.

If the wall voltage is 220V and the operating current is 31A then it draws 6.8 KW making almost exactly the same efficency as the unit I posted the graphs for 73-74 percent efficent (5KW Out / 6.8KW in)

This is of course ignoring the whole RMS power thing on the AC side but I think using the same easier math when comparing one cutter to another then things are fair if not perfectly accurate.