When I speak of efficiency, I'm referring to power consumption. BFL's 65nm based products are somewhere between 50-60% more efficient than ASICMiner's current 130nm offerings. While this hasn't mattered much in the past as operating costs are currently negligible, this will change as operating margins for miners continues to contract. Eventually all but the most efficient ASIC gear will be forced offline as they'll cost more in electricity than they're generating in revenue. Bitfury's 55nm gear shipping is significant in that it's the first gear to take the efficiency lead away from BFL.

As you said, the auction that you linked is for Oct/Nov delivery. Dave at bitfury has suggested that bitfury chip orders would ship early in October and finished products would likely ship toward the end of October. This is one more link in the chain we'd have to rely on and the potential savings we'd get by going with Barntech's auction over a direct pre-order purchase at megabigpower would seem to offer  a poor risk/reward profile. 

Cheers.