I'm a bit puzzled why you consider the sandwiches so unfriendly. If you add a Kroll tailcap and tell the user to just use the tailcap to operate and warn them the sandwich is loose when they change the batteries they are set. I suspect most people can deal with that pretty well.
IMO the result is pretty darn slick. The 2AA MM form factor is very nice. The 1W sandwiches w/optics are bright and have a nice beam. You can run whatever random batteries you would like.
The only thing that really bugs me about this setup is it is not as waterproof as I'd like. I suspect I want a lot more in this regard than most people.
I purchased a UKE 4AA eLED and PT Impact XL in hopes to find a good emergency light. I was very disappointed in the brightness of both lights and fine the beams only so-so in each case (but they are different). I also find the switch in the UKE 4AA lacking and both also have their own battery loading issues (I'd rate them on par with dealing with the loose sandwich in the AA MM).
In the end, I think you just are not going to get a very bright light in a plastic model, but to my knowledge there isn't a good alternative.
I suppose the ARC LS w/2AA would be an optimal solution, but it is a pretty expensive route to go. Certainly it doesn't fit the model for my emergency lights.
Ironically, I find the SL 4AA 7LED a better light than either the PT XL or the UKE 4AA eLED. The switch is much better (and it has a switch). It is about as bright as the others. The only downside is it is a bit more flood than I would like. I mean it is REALLY flood. Of course for some applications this would be good. Oh, and it is also a bit more blue.
In regards to the Turtlelite, I have a TL II which is nice, but not very bright (obviously). I did attempt putting a LEDCorp ProBulb in it, but the issue I ran in was the bulb needed to be height adjusted in order to get proper focus. This may be less of an issue with a side emitter, but I think you run a bit of a risk with fixed focus lights. Also, I think it was an improvement, but hardly worth the effort.
Here are the pictures if you are interested:
http://www.navitsky.org/lights/turtle/turtlelite.html
In the end, I think the combo MM AA + glass lens + Dat2Zip Sandwich + Kroll tailcap works very well. I don't think it is harder to load batteries than the 4AA lights mentioned here and it is bright, small and has a nice user interface. Perfect, no, but I'm still looking for that one!
-john
[Edit: Oh, and I agree with Paulr in regards to the Reactor. I *really* dislike these lights. Too bad, they make a great single AA LED light!]