David, I had a similar experience here in Toronto on a cold, though not freezing, drizzly day a little over a year ago when I was shooting the Zombie-walk. I'm not sure how many pictures I lost, but there were a few just before the bizarro lock-up. I had had a situation once or twice before when shooting concerts where there had been a lock-up; but the situation was cured by taking the battery out and putting it back in. Not so with the zombie walk. By the way on that Zombie Walk I was using a Panasonic Gold card, not the much-dissed Sandisks. The good news is that nothing like that has happened since, and I don't baby my M9, though I'm more careful, and have especially cut down on chimping when the red light is flashing.
Of course something like this sucks.
I'm using an M9 for 1.5 years and a MM for about 1 year and have never encountered any issues. I use only one type of SD cards (LexarPro 16GB class 10 UHC). I never delete pictures in camera, I do not use any folders. I download at home put the cards back in the camera and format the card. I'm running an older firmware and will NOT update because it works for me. Guess I'm just lucky 😉.
I also don't delete pictures in camera. I have recently bought a couple of Lexar cards, but have also been using Transcends, and haven't tossed my Sandisk Ultras. I have not done the most recent firmware upgrade, because since last year's burn-out, there has not been a problem.
I have 2 M9s and they have never played up. BUT:
1) I shoot them like a film camera, usually waiting for buffering to stop before taking the next shot ( at most, 3 in quick succession).
2) I never review the image whilst buffering (well, very rarely)
3) I don't allow the battery to get too low on juice.
4) I never delete images from the card
5) I upload images to the computer ASAP then in-camera format.
6) I don't use them in anything but a normal climate
...
Pete
Pretty much what I do now, though I recently did use it (I don't have two) on another drizzly, though not so cold day. When the rain's heavier, it's time for my E-M5 and body cap lens (I know the latter isn't weather-proof, but it's small enough for me to mostly keep the rain away from it)
Leica should have rebadged them. There must have been, but I can't recall an instance of the Epson(s) having a problem ... Anyone?
The Epson was regularly blasted in this forum for problems, especially shutter failure. One of mine made two trips to Steve's, and he could only fix it once. At one time, I had to send both of my bodies to Steve's for repair (and as I said, only one repair was successful.) Currently one works, and I'm not sure whether it's worth it to me to send the other one to Japan for repair.
I haven't seen a posting about shutter failure for a while though; maybe I was inordinately unlucky.
David, I hope that your M9 will not have the problem you had in Rio repeat. My experience since my crash should give you some hope in that regard.