I’m also in the reluctant-to-use-lithium-ion group. I do have two XTAR 18700s and a few really impressively bright XM-L lights, but apart from that I find NiMH to be a lot more fun. I’m generally safety conscious and I take care of my stuff, so I don’t really enjoy Li-Ion with all the warnings and the risk of easily ruining the cell or tripping the protection circuit.
Yeah, my most used 18650 light has a driver-side-low-voltage protection. (Shiningbeam S-mini at 3.0V) And I just run the light down till it shuts off, very convenient.
THANKS! So the D7 is only about 0.5mm thicker and comparable walls vs the 2100 so it should be a good alternative for a high quality host.
SB has had the clip for several months, so hopefully chances will be good for your next order there. I did the same wait even though I just don’t like the fit of the SF clip on the 2100. I may buy a couple more S clips next SB order, though. 
Kumabear told me that he has measured the Roche to be roughly 18.45 mm in diameter and therefore many of his cells won't fit, so if both of us have measured correctly the D7 host is substantially wider than the Roche. I have to assemble the light first to say something about the potential length issues, but having a dual-spring design I have good hopes.
I have the IO version and it is too short to take an xtar protected 18650. The xtar 2600 mah measures 68.8 long.
That's not good. Maybe I should leave the front spring away then?
Removing the front spring may work if the cell has a tall enough button top to reach the circuit board. The center contact on the circuit board is surrounded by four of the 7135s. A very short front spring may be the answer.
I am using unprotected flat top cells, so I need the spring.
Edit: I forgot that the driver you will be using is clean on the back. No spring would be needed.
Yeah, a short spring or a little solder blob might be needed to close the gap that the driver retention ring creates. This seems like a pill/flashlight design that's best used with single-sided drivers. I assume that the IO light that you own left the ring away completely to accommodate the double-sided driver??
Yes, they just soldered the driver to the pill.
Anyone take the switch apart? Wanting to know what size switch it takes since I want to put a forward clicky in one.
How are you getting on with this vectrex? I’ve built mine up with a u2 and ld25 cc driver. I love it and keep it set to low, it does get warm quickly on high, but high is probably a bit much for its intended use.
The cut outs in the tail cap allow it to still tailstand with a claw fitted, which is useful for me, I’ve just tied an edc lanyard, my edc pocket knife and this both clip to the lanyard and can be easily removed for use. It has also shown me I don’t need to go below 18650 for edc.
I have assembled mine with no driver spring, I have no issue with mode switching and I have so far not found a cell that won’t fit.
Good luck, I’m looking forward to seeing what you think when its built.
I proceeded with building the light, but encountered the whole spring/no-spring - using/not-using the driver retainer ring problem and want to explain that a little bit in detail, but I need to borrow some additional 18650 from a friend to do some documentation and some pics. I only own 2 types of 18650 cells.