I too ran a live, online auction on MFL last year. I'm usually pretty pleased with their service, but our auction was pretty disastrous. To be fair, the feature was clearly marked as BETA last season, but it was rough going. There were lots of issues with nominations, and several people complained that they placed bids that didn't go through. Once more, "rolling back the clock" on incorrect bids / nominations proved to be very difficult. Thankfully, customer service dropped in and took control of our auction and fixed some things.
Right now, my plan is to see what sort of corrections have been made for this year. If they've taken the BETA off and fixed the bugs, then we'll roll with them again. If they haven't, then I'm going to be moving the entire league to another service. The league I host there is way too basic to justify the cost of MFL, especially if they cannot properly handle a live auction.