I've been using mint for the last 6 years and though I like the polish of regular ubuntu's unity look, it just never seemed snappy enough no matter what hardware you ran it on. UMate 15.10 has definitely replaced mint as my go-to now. Its just what was needed.
As far as a new side panel goes, I had an idea a few years ago that may be of interest. Instead of having folders on the desktop and or having to dig for them in menu's, what about a "drawer" system where you can add little tabs that stick out slightly from underneath the side panel. The default would be the home folder of course. Once you click on the tab it opens like a drawer or narrow window across the width of the screen (depending on the amount of items you have in there. On a touch screen, you could just slide your finger to pull it out. The mouse wheel could be implemented as a quick side scroller in addition to the usual touch fair. You can add as many of these quick tabs as one has real estate to do so. Obviously windows would have to be minimized to see the tabs but this is true of desktop icons as well.
Anyhoo thats my 2 cents.
Keep up the good work dude. Cheers