1) block finding times can oscillate for serious amount of minutes, so there can not be fixed ending time of auction, feature people like and may be essential for successful auction
If you have any ideas how to solve these two issues I would very much like to hear them.
I think people mainly want the rules to be the same for everyone. So fixed number of blocks might be better than fixed time.
It only goes against sniping but, in my view, that's a huge plus!