Rob - I can only speak for myself; here's where I see the advantage. If I leave on a trip and pack the M8, dSLR (pick your flavor) and a P25 based medium format kit - it's ALOT of gear. Add chargers, batteries, lenses, trinkets, etc. I've gone on a trip with more gear "luggage" than my wife's actual garment luggage! She just rolls her eyes and also grasps the magnitude of how much has been spent on gear. You can only hide so many Domke J2's before the light bulb goes on
Tally up all that gear - say $8k in a 5D2 based system with lenses, a M8 with 1 or 2 lenses and ultra basic medium format kit. It hits $20k real fast. Each system has its advantages here and there, but using all three is a royal pain in the ass. Horses for courses..., blah, blah, but I still have to drag along the horse trailer! And if I get the cajones to leave one system behind, I guarantee I'll wish I had THAT system and not the 1 or 2 that came along for day - murphy's law.
So, I like (and value) the idea (promise) of one system delivering that quality in moderately sized camera body. I can work with it with ~3 lenses --- something wide, something normal and something telephoto. Here's where price is key. If the Leica prices the S2 w/ 75mm for $17,995 which is on par with the new HY6 kit, or a P30+ with a P645 kit or the H3DII-31 --- then Leica is positioned well. Not great, but well. The next two lenses will be budget busters - probably $3500 per lens, so the kit would be $25k.
In absolute dollars $25k is heart-stopping, but I've got that much sunk in gear already across multiple systems. If Leica prices it right, I can see myself switching, but with alot of anxiety attached. As others have said, it needs to be solid from day one. Spending that much to go through a year of firmware & hardware & software messes isn't worth it.
I'm very interested, but Leica could squash that interest with the wrong price tag. If the price is right, then I'm guardedly optimistic. I'm very curious to see how Hasselblad counters Leica's new system.