I don't own a Q, wasn't particularly enthused about it. However, I am enthused about the Q2 and may actually trade some gear to get one.
The notion of a good front-element teleconverter to give a little more juice to the 75mm crop setting, and maybe bring it out to 90-100mm as well, occurred to me. About the time I was thinking of that, I remembered that when I had the (excellent) Olympus ES-2 fixed lens, professional grade DSLR a decade or more ago, they made a pair of front element converters for it with a very large thread/large diameter optics ... the WCON-1 and TCON-1 set. I had those and they worked very very well.
I found a pair of them on Ebay in excellent condition for $30. They're sitting in my 'interesting bits' drawer now.
If I buy a Q2, I'm particularly interested in trying the TCON-1 on it. It'll take a 49mm to 62mm step up ring to fit camera, I believe. I expect it will vignette on the full frame 29mm field of view, but when set to 50 or 75mm cropping the vignetted portion of the frame will be outside the frame lines, netting a 16Mpixel 75mm and a 6.6 Mpixel 112mm lens setup. What the WCON-1 might produce on the Q2 I'm not sure, and whether/how much it vignettes I don't know. But the pair of converters was cheap enough to buy and hold onto just in case... far less than I remember paying for them when they were new!
So the experiment awaits a Q2.