Biggest issue with the SXM is the paint, so budget for a sleeve or wrap. Second biggest issue is the fiddly battery cap. Very few reported failures/DOAs, almost no reported problems with the 510 or buttons, same with the display. It's a solid device.
@suprtrkr The Lemo series is just bad for TC builds mate. Try it with a better tank (a plethora of them out there now), and try it with Ti or SS, you may find TC is worth it again.