I got the newest version of the PT-1L Streamlight. It's a 1 cell CR-123 light. Not only is it short, it's skinny. Looks like you could put it inside a G2X Surefire. Mine has the Tentap programming and 180/12 Lumens plus strobe.

Light seems slightly dimmer than my 200 lumen G2X. I'd say about 25 lumens less. On low, it's less as well. Still it's one bright tiny light. This is my 2nd Streamlight, and I like it. The pictures do not do justice as to how short and skinny it is. I bought mine for a little over 40 at batteryjunction.

I think you'll find that Surefire tends to "underrate" their lumen output.  Glad you like the Streamlight thought - I've owned a couple and they really are good lights for the money.

I bought one of these a few weeks ago.  I really like it so far.  Only complaint, albeit a minor one, is I wish it had more of a deep carry pocket clip on it.  It would also be nice if one of the programs was high/low.  I was actually wondering if there was a way to weapon mount one.  It would be a very compact and lightweight set-up, and still pretty bright.