Cost. Look up letter to George on Mike Johnston's TOP site. George objects to being advised by the expert to get a full frame DSLR and a fast prime for several thousand dollars. Mike writes back apologetically, but details the alternative, usual route, through P&S, entry level DSLR, kit lens, better crop factor DSLR, one slow prime, another zoom etc etc, arriving at last, after two years and a lot of angst and not many good photos, arrives at last at Mike's original suggestion, having spent in the end, only as much again as would have been required at the outset. That's how I feel about the M9. Yes I got the Fuji X100, and from there is was either the X Pro 1 and three lenses, or the M9 and no lenses. And the M9 is now a reasonably known quantity. Having proved my patience with, really preference for, a fifty year old film Leica, I am highly likely to be content with my several thousand dollar M9 for the whole life of that camera, which should at least be as long as my oldest digital, 8 years and likely longer. I can't think of another lens I even want at this point, except of course the 50 Lux ASPH which I tell myself I will never waste money on. But in the end I will, almost certainly second hand.