My friend had this mill already 6 years ago. When I started to fiddle with it, it turned out to be wonderful kitchen utensil. In my own household is now also such a mill in operation - after 3 years they served still perfect. No signs of wear or similar Filling the Twin I think is not a problem if you do not just want to bring in the 10kg-sack in the mill the pepper. Commercial packages are quite compatible with the filling ports of the twin. Of course there are a few crumbs, before leaving the mill, as any remnant be knocked down by the shock from the grinder. However, I personally nothing of covers, one must take off every time before you can use the mill - just when you need quick short season which in the kitchen. Settings from coarse to very fine without any further problems.
Conclusion: very practical and also on the dining table a blast.