I think something like this is the most sensible way to do it. The 1mil is a tad shorter than the old parses, but the 1.5 is a tad longer, so either way some cool downs are going to be used more or less per class than they were. My favorite part of the "kill the dummy" style is it essentially eliminates the possibility of doctoring parses, or at least makes it much harder.
The dummy also seems to ignore the killing blow as it despawns, so the number will never be exactly the hp of the dummy. However, this should be the same time difference for everyone, so we can still use "time to kill" as an appropriate comparison between parses.
Yeah, I'm thinking 1 million HP mod until NiM DF/DP (or w/e the next tier is) gear comes out and switch to the 1.5 million HP accordingly. And yes, it would make doctoring much more difficult to do and much easier to spot.