My results on 60D:
- sometimes it takes the bracketing correctly, but slow (just like before)
- sometimes it takes first shot at 0 EV, then a small delay, then all the remaining shots are taken quickly, but all of them (except the first) have the same exposure.
Example (5x2 EV, speed tweak on, everything else default):
- 1/500, 1/2000, 1/125, 1/8000, 1/30 (slow)
- 1/500, 1/2000, 1/2000, 1/2000, 1/2000 (fast)
This is with both high-speed and normal continuous modes. I just take a few bracketed sequences with the same settings, and the odds of getting either behavior seem roughly 50/50.