I have found the 2500 iso photos all but un-usable, full of nasty lines across all the photos and way too much noise, don't know if there's anything to upgrade on the camera or what photoshop to use, but the results are terrible, nothing like the photos I see here 🙁
Tom
Tom, I made exactly the same experience, when I first started to shoot a M8.2.
I used Nikon DSLR and a R-D1 before, which behaved quite different from the Leica sensor.
A few points to consider:
1) It is eminent, to not underexpose with the M8/9 at high ISO - underexpose and it will give you nasty banding. (I try, to always overexpose by 1/2 stop and it's fine in PP)
2) Which software are you using for processing your RAW files?
Some behaves better than other. I also find Leica high ISO JPGs, to be very well handled regarding the nasty banding.
3) "Hide" your shadows (underexposed areas) in your processing.
Many (especially BW) images are developed very contrasty or/and with more wanted black clip off, which effectively hides nasty banding/ raw noise.
4) All images, displayed here show likely the best possible look regarding noise/ banding, as they are likely carefully selected and most importantly - they are all downsized web JPGs, which naturally look much, much cleaner, than printed on A4 or A3 !!! Blow them up and most will show some ugliness in the shadows ;-)