Originally posted by HeavyD I really am leaning towards going back to Canon
the grass may indeed be greener on the other side of the fence, However you still have to mow it.
the burst mode in full E-TTL II still tends to underexpose the subject, I prefer to use my flashes in full manual mode instead of trying to coax the correct exposure out of whatever pseudo TTL systems manufacturers use.
Try using your sigma flash in manual mode and for a start use it at 1/16th power, you should get a decent burst rate at that power level on most flashes, and make sure your batteries are in decent condition some types of batteries when used in flashes can cause the recycle rate to drop so keep that in mind.