Runtime should easily be more than adequate for your uses at the lower power levels, though I haven't measured it.
There are no protected 10180's as yet (too small a case for the protection features now used in other batteries), but there is no reason to be unduly concerned about battery failure within the light - these Peaks are really solidly built, especially those in SS and heavy brass. The primary danger with unprotected LiIons would seem to be in the charging, and charging the beasty little 10180's is a pain. The best solutions are the purpose built chargers described in the Battery sub-forum.
Be very careful using Nano's for 10180's. AW's Charger Reference Guide shows that even the Nano AAA puts out too much current for these batteries. I know many have reported using them with satisfactory results - BUT... I have both Nano AAA and Nano 123 chargers and all of them for some reason bear the identical label: 0.45A, or 450mAH, which is the same rate at the WF-139 and which is very clearly much too high for the 10180. AW lists the Nano AAA (which is no longer made) at 150mAH so either some or all were built with the lower charging rate or some were simply mislabeled.