I have a two roller and three roller (three roller is actually monster as crankandstein hadn't opened back up yet) Crankandstein and now have my 3 roller Monster Mill coming in soon. The Crankandsteins look the same now as they did when I purchased them years ago so I feel I can comment on the quality of them. They are by far the best mills I have purchased. I also have the Barley Crusher, which is why I went with Crankandstein (one roller on the BC would constantly just free-spin causing me to have to adjust my cranking all the time). I have never had a problem with any of my other mills and have been using them for years. I motorized my Crankandstein/MM and have kicked myself for not buying these sooner as it turns 30 minutes or more on the BC (hand-cranking as the BC is horrible motorized to me) into literally a couple minutes.
The occasional rock gets past me sometimes and is no problem for the Crankandsteins, the BC would seize up. I have not noticed any problems from the rocks and other debris getting through either. I had left my 2 roller Crankandstein out while I deployed for six months and got back to a rusty mess. After cleaning the rollers with a brush it works just like it did before I left. These things are really awesome.
Either mill you choose will be more than adequate for hand-cranking, but to motorize I would stay away from the BC. And I only bought Monster after my first Crankandstein, because after the split, Monster had their site up first and the ruggedness was just a bit better than the old Crankandstein (although this is just my opinion and is not based on any scientific data). I was in the same boat as you a couple weeks ago (left most of my brewing equipment back in the states), and chose another Monster Mill based on my use of the Crankandstein, BC, and MM, plus the MM has a way better hopper. Unfortunately I will be hand-cranking until I return to the states and then putting this one with the motor in my garage for many more years of happy brewing, hopefully.