I would also like to mention that Stihl specifically says that these saws should always be started in the START/CHOKE position, even when warm. It seems very counter-intuitive, but that's what they're saying. It is even mentioned in the manual. The only two saws I have personal experience with actually doing this were a 362C-M (a friend's) and a 441C-MQ (mine) and in both cases it kept the saws running normally, even though in both cases the saw would sometimes not start on the first pull, so we'd flip it to RUN and it would immediately start. It did, however, run normally as long as we started in the START/CHOKE position first.
Oddly enough, the 661C-M and both of my 261C-MQ saws start and run fine, once warmed up, using the RUN position and not starting from the START position.
I can not imagine why some models are very picky about this, and others are not. At some point I have had to reset the M-tronics on all of them... when I took them to Colorado, for example. When I changed the fuel I was using. When the hot part of summer hit and the temps ran over 90* F, or after doing a muffler mod. It always fixed the problem right away, which in all fairness, is a very cool thing. Beats the hell out of having to tune the carb up everytime these conditions come up, like I do with my non-Mtronic Stihl saws.