Found it! It was in the opensource toolchain instructions:
http://makergear.wikidot.com/m2-getting-started#toc4
<snip>
If your M2 has a V3b hot-end, use 215C for the PLA included with your machine. If you have a V3 hot-end you should use 195C for PLA. The V4 hotend can use v3b settings, but hotter may be needed at higher speeds.
If you have already installed the filament spool holder, filament guide arm, filament guide tube and the spool of filament itself, you can now perform your first test extrude. Feed the filament up through the hole in the filament guide arm, through the filament guide tube, and over to the filament drive. If the end of your filament has any bends or kinks in it, cut the first several inches off, preferably at a sharp angle. Feed the filament into the hole in the top of the filament drive, return to Pronterface, and set your nozzle temperature if you have not already. For the V3 style hotend, 195*C is good for PLA; V3b style uses 215*C for PLA. Then click Extrude. The extruder drive gear should move and grab the filament. Press Extrude two or three more times; if the filament continues to feed smoothly, click Extrude 5-10 times; continue until filament starts to come out of the nozzle smoothly.
<snip>
So, same as v3b, or possibly higher....
cheers,
c