I recently shopped around for the "ultimate" grain mill and went with the Mashmaster. It is a serious piece. I owned a Barley Crusher for a few days before I got the Mashmaster and they are not even comparable.
Some cool features of the Mashmaster:
Thick side plates that tie the whole assembly together. Most mills only have one plate on each end and nothing on the sides (or flimsy, thin aluminum sheet metal on the sides like the Barley Crusher). The problem with this is that the mill will only be as strong as what it's bolted to. Flexing of the front plates will cause bearing misalignment and can lead to binding.
Stainless steel rollers
Gear driven (reduces stuck slave roller and grain shredding)
The cover that goes over the gears to prevent grain from getting crushed by the gears is a great idea and is nicely machined. The whole mill is really nicely machined.
Both ends are adjustable (I actually can't believe there are grain mills out there that are only adjustable on one end)
No "grain engaged" gear teeth like the Crankandstein. The Mashmaster has real gears that maintain mesh throughout the whole gap range. When the drive roller makes on revolution, the slave roller also makes exactly one revolution. There is not, and cannot, be any slippage. You probably can't say that with the Crankandstein. There is a picture of the underside of the mill that shows the gears on the website linked above. They claim it's the "Only geared roller mill on the market that is fully adjustable at both ends." I think that's a true statement.