Out of curiosity with the DR observations I went back and looked at the original RAW files from the '07 pictures. They were taken with a D70 & 105/2.8 lens. They were all shot at a +0.7EV probably because that camera tended to underexpose somewhat and that was pretty much how it was always set. The shot below wat the least overexposed of the bunch and still has no real detail in the flames.
Not to drag out such things, but the somewhat unnatural coloring in that middle right flame is a dead giveaway that the highlights there were blown... no amount of adjustment is going to get it back.
(Forgive my technical side coming out here with this discussion!)
Also out of my own curiosity, I checked my shots of FotLK's fire dancer (which were pretty bad across the board - I was holding a sleeping kid at the time, for goodness sake!) and I got fairly inconsistent exposures, probably due to spot metering. If the flames were in the "spot", the exposure varied greatly from if the body was in the spot. I also had a +1.5, I think this was for the rest of the show. Obviously it's not a bad idea to flip this to a -1 for the fire scene.
Here's the shot that is most close in terms of exposure to your finest ones. (And don't get me wrong - this photo is pretty bad, it didn't "make the cut" so I didn't spend time on it, but with some raw processing, I might be able to extract a little more detail from the highlights. On the other hand, it has the head, not the rump.
) I think it's got a pretty fair amount of fire detail, all things considered - and it is, I think, still more exposed than your "flaming butt shot".
In fact, that shot is the same aperture but a half-stop higher ISO and twice as slow of a shutter speed - that's a full 1.5 exposure steps by my math, and we can assume pretty consistent lighting for this performance, I'd say.
I'd say, break out the ol' D300 (if you still have it) and I bet you could get pretty comparable shots to the ones you just got.
I'm obviously still trying to figure out exposure, etc. 
