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!
So, you would be interested in auction that may and in 5 mins or 20 mins, and nobody knows when? My hunch is that sellers would not like this, they love when bids jump high in the last seconds of the auction. Deny them that profit and they would not want to bring their goods to such an auction system.