I can't say as I've ever done a FSBO on a property, but I have done an auction. Granted, timing is everything and I'm not sure how well the experiences would have translated post real-estate pop (we sold Summer of '07, closed escrow and signed paperwork on August 17th - day the panic reached a crescendo and finally popped - buyer's mortgage wasn't approved until *that* morning), but it was still enough of a positive experience that I'd be tempted to do it again if the opportunity arose.
Now, what were the benefits we encountered with auctioning? First off, we only had a 3% commission taken off the top by the auction company instead of the traditional 6% by the real estate agents. The agents we'd had walk through and assess selling value were figuring we'd only get around $160-165k on the regular market selling traditionally, but we decided on a lark to try auctioning instead. As such, since we were permitted to set a minimum value for the property to auction at, we set the low end of the appraised selling value. We also had the option of stipulating escrow terms in the winning bid contract of 30 days, and the winning bidder had to lay down a non-refundable if escrow terms were broken 10% deposit, with 70% of that going to us if it was. The auction was an intense and nerve-wracking 15 minutes after a 90 minute open house, but when the dust settled? The house sold for $195k. $30,000 more than the traditional agents were figuring the place would sell for. The best part? We only had to clean the house up once for display and knew with relative certainty the date we would move out so long as nothing went sideways, and if it did, we got money to cover that for breach of contract.
Think about it, though. Auctioning is the ultimate form of high-pressure sales. You have a captive buying audience already serious about purchase with money in hand, they're on site at the property where it's a tangible purchase immediately after a walkthrough and no time to think things through or sleep on the decision or re-visit the property, no bargaining back and forth opportunity for days with offers and counteroffers, and you have buyers directly competing against one another for ownership.
YMMV of course, others may have had bad experiences, it might be a regional success thing, we may have lucked out with the tail end of the housing bubble, etc. etc., but it's still something worth at least looking into as an option because when it works? Boy howdy does it work!