Value
Value
Interesting question. The answer really is "it depends," because the gist of the question is the relative marginal value of the M8 vs M8.2. That varies from person to person for several reasons.
One obviously is cost. The M8.2 costs about 2X an M8 - a roughly $3000 difference. To some, that ends it; get the cheaper one. And yet, to others, a $3000 difference may not be that significant.
Another variable is the maringal value of the "extras" of the M8.2 and what it would entail to retrofit the M8. The new framelines probably appeal most to most people, followed by the softer shutter (some would prefer the faster shutter of the M8), and then the sapphire glass and vulcanite. However, assuming one wanted all of these things, going through the upgrade program for the M8 will cost $2030. So the value to a current M8 owner for the upgraded camera is about $5000 ($3000 base + $2000 upgrade fee). The additional hidden cost to the upgrade is the loss of the use of the camera during the indefinite period of time (weeks or a few months) during which the camera is in Leica's hands.
The upgrade to the M8 will not include cost of the stealth mode (delayed shutter recock), snapshot mode, and greatly improved manual EV adjustment. The real question, then is whether these features are worth the roughly $1000 beyond the cost of a full upgrade or, whether in aggregate, these features plus the new framelines, sapphire glass, shutter, and vulcanite, in aggregate, are worth $3000.
Personally, I'm either going to stick with my tried and true M8 (holding out for an eventual M9) or trade it in for an M8.2 (paying a cost of about $3000.