As far as I know fully regulated MC-E or P7 lights on just a single 18650 don't exist. If you want flat regulation for an MC-E or P7 you'll need at least 2x18650 (don't ask me why, still unenlightened).
I'm also looking for a compact MC-E or P7 able to run on a single 18650 (I use gray Trustfires 2400mAh). I already have a Spiderfire P7 which is a great (budget)light, though it's direct drive. I also want the best possible regulation for this kind of setup so now I'm lookin' into/waiting for the next flashlights:
MG-PLI
MG RX-1
4Sevens MC-E
Epsilon ED-P71
Elektrolumens EDC-MCE
Wolf Eyes Explorer
If flat regulation is a must, I'd go for the new Eagletac M2SC4. Though not quite EDC, it's more compact than other 2x18650 lights because of the side by side battery setup.
Good luck picking one, trust me, you'll need it (been lookin' into this for 3 months already)...