Had a hold and a trigger rattle on the M2 at the weekend. Feels really good in the hands (as do all the ultralight frames from DYE IMHO) and the trigger (presuming it wasn't just especially nicely set up on that one) was superb.
Main problem for me, as always with Dye Markers, is that they tend to be picky with maintenance and the fact that there isn't the high level of customer support that Planet offer. For me, even with the extra cost, the ability to send it direct to the manufacturers, couple with previous very good aftersales from Planet would edge me to the CS1.