So I have been running the latests, that have been posted anyway, dual extruder setup (mounting and firmware).
As of today anyway here is what my feed back is.
When using PLA, the heat creep for T0 at least is pretty bad (even when only printing with one extruder), so looking at ways to remedy that.
When only printing with one extruder, the second extruder stepper motor gets hot (probably being told to hold and is energized) so, I have been unplugging it when not using the second extruder.
Also if using slicing software other than Slic3r (for example Simplify 3D) you use your appropriate settings in the Starting G Code script “M218 T1 X0.0 Y-53.5”. Not 100% sure if you only need it in the starting script or if you need it in the tool change script as well.