It's worth mentioning that there is a huge library of scores on IMSLP, including critical editions such as the Bärenreiter Neue Mozart Ausgabe. There's also a growing number of scans of first editions and composers' manuscripts.
I've cropped thousands of pages with ForScore: it's no big deal. I've set up a gesture (press and hold with three fingers) which brings me directly to the crop screen. ForScore immediately and automatically crops away any empty margins. It's usually fine like this, but if I want, I can adjust it manually. Staying in the crop function, I go through the score and crop each page in turn, then save the whole piece. It's a matter of seconds for each page.
