I just bought a Maglite ML300 2D last week. I've been looking for a more powerful EDC that uses standard cells for a while now and with the high output, simple mode switching, and decent battery life, I finally pulled the trigger. A 2D is rather large for EDC, but I'm getting used to it. I'm just glad I didn't go for 3 or 4 D.
As for batteries. I'm currently still on the 2 Energizer Max cells that came with the light and I bought an 8 Pack of Rayovac for spares. I am going to investigate Rechargeable cells as a matter of course. My main concern is the current drain, I have already checked perceived brightness and NiMh appears to be just as bright on high power, but I will do more comparisons in the near future.
Mags run fine on NiMH's, though I generally run my 2 and 3D cell LED Mags on single 26650's in adapters – a lot lighter than D cell NiMH's and there's only one cell to charge, not to mention no leaks that are always a possibility with alkalines.