This sort of thing is likely to be a template edit issue - all the data is exposed, so it's not going to be a difficult thing to achieve, but adding admin options for this sort of thing really only serves to make the base product more subject to bugs and unexpected behaviour, not to mention the performance penalty of carrying around so many options and having code to support them.
Would it be a huge job/feasible/desirable to make the member pop up visible on hover (after a second or so)?
I propose it would work just exactly like the topic preview on hover...
I just think it could be neat to have it that way - read an interesting post, and think "let's have a look at who this person is," hover for a second, mini profile pops up, and then if prompted to have a more indepth look, have the avatar click to go to the full profile page, not the same mini profile, so in effect what I have suggested would save a click, instead of having to click to see mini, then click to see the full profile, you can hover to see the mini and click for the full.
Resume scrolling and the hover pop up goes away just like the topic preview.