For hummingbird shots, blur could still be there even if you use a multi-flash system. At least from photos I've seen. One thing I haven't been able to do is to get the whole bird in the DOF.

I think shooting hummingbirds is not that difficult if you know where they hover. I have a series of three shots with the hummingbird hovering, first facing me, then turned to its left and then right and I got all of them even with MF. It seems to me most hummingbird shots are made when the bird is hovering or busy feeding themselves...at least I haven't seen a hummingbird in flight shot like those of swallows or bald eagles.

Here's a unique set of hummingbird photos from somebody else:

http://www.birding.bc.ca/community/viewtopic.php?t=2151