I have not had one reboot since installing the extended battery. I did have a "power off" yesterday. Was using my phone, press the screen off button, laid it down, then about 1.5-2 hours later I picked it up and it was turned off (40% battery when I turned the screen off, 37% when it came back on)
LG Spectrum -- Rooted and running CM10.1 official M2 thanks to TDM (and too many others to list).
B&N Nook Tablet 16GB -- running CM10.1 with 10 finger multitouch