I red something a long time ago about the filter on the "new" cameras being sensitive to the cleaning solution a lot of us used in the past. I use Eclipse. I'm sorry I can't be more specific since it was so long ago.
My question is thus what do I need to know about wet cleaning the 1DSMKIII's sensor?
I'm not sure if Eclipse is harmful, although a less hardened coating might be in use to reduce sticky dust. One thing is for sure, the IR filter is extremely thin compared to earlier full frame 24x36mm models (before the dust shaking was implemented) to reduce mass, and the relatively large surface will make it flex and break with only moderate pressure! I know of several people who broke theirs during wet cleaning. The whole sensor assembly will need to be replaced, and it will be expensive. So if you have to use anything else than a brush, don't apply pressure! This may be the first camera I will send in for cleaning when it gets dirty ...