I think "The Torch" is about the size, but smaller than a 2D light, so obviously can't fit 4 Ds inside..The 64623 lamp in there will run from 4D LiON.. however i wouldn't run them direct drive, you are virtually guaranteed to ruin the batteries the first time you use them. (DD of LiON with a high-power incan light).
From my testing of the 138, the 625 and 623 lamps.. the 625 is the winner if you want the brightest light.. 3000L regulated output with the 'Mag625'. The 623 can output more light with fresh cells, but even direct-drive from 14.4V it won't appear as bright as the 625.. but it's more homework and cost.. when you see the price of a turnkey light based on the 625, you'll not be unhappy you saved money buying the torch.
Additionally.. you really can't tell the difference unless you are professional flashlight maker between the different 100W lights unless you know the difference and are looking for it.. 2500L from a USL.. 3000L from the Mag625..
The chart for the IB 1400 is
here (i'd link directly but that's against the rules).
The cell will start at 1.3V initially.. estimating about 30mohm for circuit resistance.. that gets you 15.3V to the lamp and whoaza.. 4200L.. somewhat short lived.. 120mAH or 42 seconds later, the cells will be at 1.25V/cell or 3700L.. 2.4min to 1.2V/cell at 3200L.. then you get a nice burn to 800mAH where it'll be at 1.15V/cell and 2700L.. 5 minutes.. 1075mAH or about 6.5minutes.. 1.1V/cell 2350L.. 1300mAH to 1.0V per cell and 1680L.. 40% of initial output..roughly 8 minutes of quite a ride.
The BURST at the beginning has got to be quite a rush.. the LiON Ds drop to 14.2 or 14.4 nearly immediately so the 623 never seems brighter than the 625, in the case of the torch, looks like quite a different story.. the color could be orange as a pumpkin and an extra 1200L is most definitely going to seem brighter.
So.. the results.. you will get quite a 'burst' with fresh cells.. and even the nominal voltage looks like it'll net you about 2900L In lumens per CC.. i would be betting on the Torch as the reigning champ... i can absolutely guarantee instant smiles with this light, just like the USL, or any Mag100.. but when you factor in the micro size.. wowza.
Take note of the mention of being meant for bursts of use.. a full burn on this light would probably break the lens.. i've taken out 3 UCLs so far with Mag100s and they are usually running about 120W.. The torch starts out puttting a PUNISHING ONE HUNDRED SIXTY WATTS to the lamp! There is a very good reason it's brighter :-D
Figure on a third of those or 53W getting back even through the finned head into the body of the light.. a full burn would probably get the body up to an AVERAGE temp of 130F.. the head should get over 200F on the bezel.
So.. have a blast, just be careful.. 160W is most definitely not a toy.. a USL start life at about 125W, drops to about 120W nominal.
fun stuff keep up the good work
-awr