The problem with the Gemini 20, for me, is the 20 gram capacity. That's only 308 grains.
That's enough capacity for most operations being performed by most reloaders, but nowhere near enough for what some of us do.
I also don't like the 0.001 gram resolution. That's 0.15 grains, which, of course, gets rounded up to 0.2 gr. ...but that's just me being anal.