It will function but it can't really handle the heat on high. I haven't risked it, but I've heard it gets super hot within a few minutes and will probably shorten the life of the led.
That's all I've been using in my MiNi 123. It does get a bit hot when left on high for a while, but I've gone the distance to "empty" the cell and have had no problems.
Never thought of the borrowing angle...but my mini would never be the light I handed to someone for use without me present and it's always with me so I don't worry about anyone in the house just randomly grabbing it.