Bought my Monster Mill crusher several years back. When they were new to the market. Opted for the 2" hardened steel rollers (after conversations with the maker). Stainless didn't have even close to the life span of the hardened steel rollers. Upgraded from the smaller, to the 2" diameter rollers. At the time, I was replacing the Barley Crusher that just wasn't up to the task. I used my DeWalt hammer drill (18v) to run both and that was 'OK'.
When I got back into brewing earlier this year (after about a 5ish year gap) I decided I wanted to put the mill on a motor. Looked at my different options and ended up getting the motor assembly from Monster. I had to make a spacer/riser for the mill, since the motor was setup for their 3 roller mills). But that was easy enough (have milling machine, will make). Made a cart to hold both (locking caster wheels on it) so that I can store it easily and then just pull it out when needed. I also made a 'lid' for the hopper to keep things from going into it from above.
When I originally bought the mill, I also got the hopper extension. Gives me a 33# grain capacity. I've put almost that much into the hopper before.
Crushing grain with a drill would eat through batteries pretty fast. When I was brewing with a friend (we would both brew our own recipes at his place, so two mashes going at one time) it would either deplete, or damned close to it, a single battery towards the end. IIRC, there were a couple of times where I was glad I had a second battery with me (we needed it) even though the first was fully charged. With the amount of torque the drill used to get the rollers started, it was a bit rough to hold onto the drill. I didn't have it mounted to anything (the drill) since I used that drill for everything.
Now I have 20v tools (got rid of the old 18v tools) and had no plans to get a drill to use with the crusher. I know plenty of people do it, but I can simply load up the hopper, flip the switch, and watch the grain rain into the catch container. Depending on the recipe, will determine if I need to stop the crush to put a second container under to catch the grain.
IF I was on the market for a new mill, for home brewing (not commercial level), I'd be looking at another one from Monster Mill. I'd probably go with the three roller, geared model. But, since my current Monster is still healthy and happy to crush my grain, I'm going to keep it in service.
I'm of the mind of "buy once, cry once" in most things. While there are higher cost/tier barley mills out there, I'm very happy with what I have. Solid customer service also goes a LONG way with me. With the amount I'm currently brewing, I don't expect to have any issues with the Monster for my lifetime.