Would 4 AA's, Alkaline or LSD NiMH be good enough to power a MC-E at maybe 2.0A for 1 hour?...I guess I am attracted to AA's because of their popularity among most general users.
There was just this post about why no Crees in a 4AA form factor yesterday. Maybe the question is more "Does anyone want the 4AA form factor?" than any technical considerations about batteries.
Personally, I think 4AA like the SL ProPoly or UK eLED is a very handy size but at least among the lights aimed more towards our kind of crowd, 4AA definitely isn't something you see nowadays. If you ignore custom builds and drop-ins using Mags, all the new lights have avoided the 4AA format.
Hmm, come to think of it, I can't really think of any metal-bodied lights that are similar in shape to the ProPoly. Maybe fabricating a non-round host like that is not worth the added cost, and any polymer-bodied light won't take the heat of a multi-die emitter very well. I think cramming 4AA into something like a 4AA -> 1D shape makes for a light that is too fat, at least for my hands.
However, if we're just talking wishlist and maybe a custom build, I think 4AA NiMH and an underdriven 5A tint MC-E would be just peachy!