Hi all, just an update about my M9 and sensor replacement. I got it back today from Leica NJ. Based on the paperwork, it *appears* they replaced the sensor, but I haven't had the chance yet to actually shoot with it to confirm (busy all day for the next couple days). Funny thing and perhaps typical Leica, after the confirmation of receipt email I received from them a couple weeks after sending it in, I didn't hear anything from them until I received a UPS shipping notification by email yesterday. Zero additional communication... no confirmation that the sensor glass was indeed corroded (it was), no inquiry about trading to the M240, etc. Maybe something ended up in the spam folder and got deleted, or they read my comments here a month ago and read my mind that I had decided to just get the sensor replaced. I guess it's up to the individual to contact them about upgrade options.
Anyway, turnaround time was just about exactly two months.
If you're sitting on a corroded sensor glass M9, send it in before it's too late, haha.