I received the latest model of the M-Edge e-Luminator booklight the other night and have had a chance to compare the upgrade against the older model. Here’s how it stacked up:
The E2 is the same relative size as the E1 and lays neatly along the spine of the M-Edge case.

There have been several modifications to the design – all of which are an improvement over the old design:
Power Switch – The power switch now resides on the side of the light housing, instead of the tip. Center position is off, and on either side of center resides the low intensity and high intensity beams. Very simple to access and operate. There is a slight difference between the 2 intensities, but not a significant one. I'll probably just use low for the time being.
Flexible Neck – The neck is now made out of enameled flexible steel. It is VERY flexible and maintains its position exceptionally well (unlike the previous version which was a bit like bending a rubber tube with a pipe cleaner in the middle).
Battery Compartment – The battery compartment now houses a AAA battery, making the compartment larger. And although the basic design of the battery compartment cap is the same, they have upgraded the materials and it seems to be a much better fit with less likelihood of stripping or popping off.
Swivel Point – This is my only concern where it comes to the new design. The swivel point was designed in the center of the battery compartment, so when you swivel the light arm up from its stored position, the top of the battery compartment descends deeply along the spine of the cover. However, if you keep rotating the light 180 degrees, the battery compartment will pass over the spine completely and lay neatly alongside the spine. Not sure how this will hold up over time with the battery compartment cap rubbing against the inside of the spine every time you use the booklight, but time will tell. My preference would have been to position the pivot point HIGH on the battery compartment, so a smaller portion of the battery compartment would rub on the inside of the case.
Battery Life - TBD
All told, I am very happy with my purchase and I believe M-Edge made some very good improvements to the design. Some people would like to see an AC adapter port for use with rechargable batteries, but I much prefer traveling lean and mean (which I believe is the intent of this particular light design)...one extra battery for a week long trip should probably suffice.