Are the diffs with long lines really worse than the diffs resulting from M-q'ing the whole paragraph whenever it gets edited?

And do you have a quick way to tell M-q to fill only comments, not code?  It does that automatically in other programming language modes, but not in Coq mode (for me).  I could figure out how to do this myself, of course, but maybe you've already done it and saved me the work...

When I split my screen in half to edit Coq with the source file on the left and the goals buffer on the right, each pane is about 70 characters wide.  Text that has been hard-wrapped to 80 or 100 characters looks *really* ugly when you try to read it in a 70-character-wide window.  And when I increase the font size one step (which I like to do not infrequently, depending on how tired my eyes are, what the ambient light is like, etc.), the window width goes down to 60 characters.  Sometimes I also like to widen the goals buffer, if there are some long terms in it, since Coq isn't very smart about putting line-breaks in there.