Just briefly here - upgraded a BTU Shocker to XM-L2 U2 (1A -1C or so) for rdrfronty, nice results. Please note it has an AR lens installed:
On Panasonic PD's (FT) w/magnets on neg. end, fresh: 3,760 lumens @30 secs
On KeepPower 3400 KumaBears, fresh: 3,644 lumens @30 secs
On same set of KeepPowers from above after 1 min of time on batteries: 181 kcd
This thing is scary, a true beast to be afraid of.
There may be a few Q's coming, but these numbers I feel pretty confident in from previous lightbox measurements (many), though I know it's not a perfect setup for sure. Also, the lumens was actually rising a little during the first 30 secs, then settles at about 45 seconds, then slowly started dropping off. SinkPAD's are doing their thing, and 20 gauge wire, Arctic Silver 5/Arctic Alumina epoxy, polished surfaces sure helps.
The only thing I've seen close to this is my mod'ed J18 at 5,000 - 5,500 lumens, but of course no where near the throw of the Shocker.
I'm wondering how much loss is coming from the battery carrier though, and if Pana PD's do that well, how would Samsung 20R's do? Or the new Sony 30 amp batts (short run though )?