holy hell....why don't you just use a power glove?
2 buttons plus a scroll wheel, so 3.
That might be preferable.

(I've never had a chance to use one though.)
I do a lot of CAD work, and it took a few weeks to convince them to incur the massive $50 expense of a G500 mouse. (For an idea of their typical mouse budget, a few of the computers there still use ball mice.) It has helped a bit with wrist and finger aches, but it's still far from ideal - mouse design is very much entrenched in making more of the standard shape. It's interesting too that gaming mice seem to have more focus on ergonomics, to allow for long gaming sessions, than business mice - presumably because no one is ever in a work environment where they're using a mouse for an extended period of time.
And couple the # of mouse buttons with the fact that I
love using keyboard shortcuts. It's so much quicker to use Win+E, then Shift+Tab, then the arrow keys and letters in order to get to the folder and files I need, rather than clicking all over the place to get there.
Wait for them to perfect brain machine interfaces for mouse control. It's not very far off. They actually have a few products on the market but they aren't mature yet.
It's about damn time.
17
You might just need to sand the contacts a little to get the patina off.
Whoa.

That looks kind of slim and tiny though. Do your ring and pinky fingers just kind of hang off the edge and drag on the desk then? I've got that with the G500 unfortunately - my pinky finger kind of hangs off the end, and drags on the desk. The
mouse that came with Microsoft's Desktop 6000 set was quite nice in that respect. All fingers have a place to rest. The problem that that sort of design will encounter of course is variations in hand size.