Thinking of taking the dive....but confused

Very briefly to help. The "M" newer models have the same - higher resolution - Foveon sensor as the DSLR SD1M with newely designed lenses to be able to match the high resolution of that sensor.

You can read more: http://www.dpreview.com/news/2012/02/08/Sigma_DP1M_DP2M_Merrill_Cameras

--
Zone8: Although I am a handsome genius, when I stand in front of a mirror, I vaguely recognise the ugly idjit standing on the other side!
LINK: For B+W with Epson 1400 (and other models) using black ink only PLUS other useful tips:
http://www.photosnowdonia.co.uk/ZPS/epson1400-B&W.htm
Cleaning DSLR Sensors, including Kodak DSLR Factory Cleaning method:
http://www.photosnowdonia.co.uk/ZPS/KodakDCS-sensorcleaning.htm
Solving back/front focus problems on Sigma and most other DSLRs
http://forums.dpreview.com/forums/read.asp?forum=1027&message=35565277
PDF format list of lenses you can print or download - covers Italian Flag YES/NO for DCS 14n but applies to others. http://www.photosnowdonia.co.uk/ZPS/ItiFlagLensList.pdf