The value of BTC has risen a lot in the few days I've been here. I notice lots of prices that are high now because people aren't used to adjusting downward quickly. Obviously the increase in value will slow down, but in a longish auction you might end up getting bids in the beginning and then no more because the BTC are more deal at the end of the auction than they were at the beginning. I'm not really saying much here, just that I'd expect people to prefer short auction lengths. Of course not too short because you want enough people to see it before it goes offline.