For what it's worth, The Featherman pro is by the far the best plucker I've used. I've rented them before and I've used off brands, but when I needed to purchase one, I went with the featherman. It also coincidently came with one of the best homesteading books I've ever read called Simply the Greatest Life by the creator of featherman equip David Schafer, who is a frequent contributor to the APPPA message boards. We have been raising 250 birds a year, next year we are going to 500 and we also raise about 40 turkeys every fall. I would say it's a little over sized for our operation, but the quality and customer service you get with featherman is unrivaled.
I've also used some cheaper pluckers, that are always much smaller (one bird at a time and definitely no turkeys - where I can easily do three broilers at a time in the featherman). They work fine as far as I've seen. I would say they all had enough power to get the job done, but cleaning is more difficult in the smaller sheet metal ones and they are heavy as a lead weight for some reason. And, as I already mentioned, you can work more efficiently and quickly with a larger tub and it's easier to reach your hand up under the plate to clean out clumps of feathers.