I had a drawer full of Inovas, MagLites, and Streamlights, all LED flashlights. My 'museum'. The 'twinTasks' were neat - incandescent for bright, LED for low. Anyhow, early last winter, I bought a Surefire 6P LED - wow! Brighter than the 6P on it's incandescent bulb - and 12+ times the runtime. I soon added a Fenix '4 in 1' Special, thank yoy CPF & Fenix Store. It has the P2D Q5 Premium head - 180L on turbo - with a Cr123. It came with extra's - including the AA battery holder & tailcap switch. I preferred the 123s - ordered 3 dozen from S-F for <$70 shipped 2nd day. Long dry spell... skip ahead...
I was buying a new S&W 4" 617 revolver - $619 - having just sold my last bottom-feeder. My 'pusher', ie, S&W and S-F enabler, told me he had more S-F E1B Backups in... marked with the LEO price of $85 (MSRP had been $110 - and no one can advertise selling S-F for less than MSRP.). Including s/h, batteries, cases, and 'LEO' prices (I'm not a LEO - just a 'good' customer.) are okay, I guess. He offered it to me for less - and $10 off the revolver... I had enough money. When I got home, I found out - via CPF - that S-F had gone up 9/1/08 - that Backup was then $149 MSRP! Next time I was in the store, I told him about the price change. He checked his invoice - oops, they cost him more than he had priced them! It's a Ma Pa store, so that was important to them. I was looking at a new two-level E2DL Defender - he made me such a price. Both lights - and lunch at Subway - and I still had change from $200... I got two deals. Of course, I am broke.... and just scavenged the freezer for my lunch - some undated home made chili - very hot chili.
I just hit the S-F 123 stash for the first time - that Fenix P2D Q5 Prem is hungry. I love the E1B Backup, a one CR123 cell light - it's clip, after my initially despising it, is a favorite characteristic now. You can clip it on the front of a ball cap's bill - and you have a 'headlight'. At it's low, 5L, it is fine for walking on the street, down the hall, or reading a map in the car. On it's high, 80L, it is warm-white, like the Fenix, with a great fill - the 6P LED being a better thrower. It's been a month of carry - same cell it came with.
The E2DL is a two cell that also has two levels - it's high being rated at 120L. It's brighter than the P2D on Turbo, supposedly 180L! It'll run over three days on low - it may just be a great survival bag goodie. While I love the E1B, it is now the same price as the E2DL, which I feel is more useful.
Now, I have been in the electronics trade since Johnson was President. I know that all secondary cells can be dangerous. The CR123 Li cells are most dangerous when you use dissimilar cells in series under heavy current draw. Don't mix brands - or used with new, especially when you replace two or more 123s in a light. I have found a great way to continue discharging 123s after my 6PL or now, the E2DL, nearly flattens them - my low current floody Inova X5 - but even that is dangerous. With care, they offer the highest energy storage density - and can produce the greatest power density, too.
Now, AAs, I like NiMH rechargeables - 2,600 mA-Hr vs the old NiCd 500-550 mA-Hr - and no memory. A great aid, if you use a lot - a programmable charger/discharger - like the LaCrosse Tech BC-900 - works with AA/AAAs. For my 'gotta work' lights, I use primaries - CR123s now. YMMV.
Now, if I wanted a replacement for my P2D... that OP's new light looks nice, althought that video put me to sleep!
Stainz