I've had an M3 for about 2 years now - gets LOTS of use, and lots of range time in and out of my Safariland 6280 (use that rig for warrant service, etc). I have had 0 problems with mine. I don't use the toggle switch, I have "remote" switches (both handgun and long gun) that I use with the weapon mounted.
I've seen the Surefire X200s, and they look like nice lights; but I haven't seen anywhere selling them under $200. The M3s, by comparison, can be had all day long for well under $100 on eBay (last one I saw was about $80).
If your budget is tight, I'd get the M3, recognizing that it might not live up to lots of HARD use. The M3X is more "agent proof" - and you can occasionally find those in the sub- $100 range on eBay and elsewhere. If you get the Surefire, be sure you know which model you want - the X200A has a very tight, focused beam, which some people prefer for the "dazzle" factor if you hit the BG in the eyes with it; the X200B has a diffused beam that's probably better suited for general search/target location/ID work.
Regards,
Kevin