I've been pondering getting a 1 x CR123a tube for my L1T v2 also. While it should give the same output as the L2T, I'm worried that the runtime will be substantially shorter: 2 x AA @ 2500 mAh each, or even 2000, vs. 1 x CR123a @ 1300 mAh. The L2T is rated at 2.4 hours on 'high' on 2 AAs (what If that's correct then I think the L1T/P2d (or as another poster coined it, the 'P2T') will run for less than an hour, more like 45 minutes, before falling out of regulation and quickly biting the dust. One other poster, I forget who, has one of these 'frankenlights' and I think he said this was the type of runtime he was getting. This really isn't bad, all things considered, but it seems a little too short to make me really happy.