I have had 2 sensor replacements (both done for free) on an M9 I bought used.
I still love the camera and the images it produces, but I no longer trust it. I'm hoping that the above post about the new non-coroding sensors is true and that my current sensor is one of those and will last awhile.
Due to the sensor issues, I didn't bring the M9 along on my last trip and while I missed it, I just couldn't risk coming back with a bunch of screwed up images like I had in the past (both my sensor problems appeared after long trips overseas for some reason).
However I'm not in the least tempted by the M240. It's fat and it has a bunch of stuff I don't need (video, live view). I think my next Leica will be a used M10 when my M9 craps out. I think of the M240 like the M5, I'm sure it's a fine camera, but it's fat and ugly and I don't want one. For the money one pays for Leica, I want sexy as well as functional or at least not fat and ugly.
Not sure if that helps you but it offers another perspective. I don't find the low ISO limiting. I shoot at a max of 640 and I push it in lightroom if needed. I read somewhere on this forum years ago about this being a better technique than using the higher ISOs on this camera and it's worked for me.