No way to get the shutter working with the old lenses
One of the C.Fn functions is "Release shutter without lens".
and, no RAW!
If you mean RAW video: that's not implemented on any CHDK supported camera at the moment. AFAIK
Ant is doing some related research on the M3, but that's all.
If you have a fast UHS card, try running the benchmark and see if you can get write speeds above 20 MB/s. My attempts maxed out just below that limit.
This camera (M10) looks like an upgrade in various ways to my S110 (and SX260).
Can I help with testing or similar?
To date, I have only done some basic testing of CHDK overrides. Doing more thorough tests under various conditions (lighting, ISO, factory image enhancer functions on/off) would probably be useful.
Also, suggestions on possibly improving camera functions / usability would also be welcome.
However, if you'd like to jump to a CHDK supported interchangeable lens camera, be sure to consider the hardware limitations before buying - the M3 offers more (ext. flash, optional EVF, more buttons and dials).