Another vote for the Preon II.
Got a black Preon kit when these were available at Unique Titanium. (No longer the case. But they do still sell Preon lights. Great to deal with.)
I decided to use the Preon I tailcap on the Preon II body. Ended up with an excellent penlight that sits deep in a back pocket. No issues about it accidentally turning on since that configuration makes it a twist-only light with the max output of a standard Preon II.
I found the clicky switch of the Preon II to be too sensative when switching modes, and the metal tailcap cover has an annoying tendency to rotate in place. Solved both issues by using the Preon I tailcap, instead.
(I use my Preon as a secondary light. For a main-use light, I'd stick with a stock Preon II.)