Downsizing - Using Estate Sales

Any full-timers out there that have experience using an Estate Sale Service? Looks like this would be a quick method of downsizing. I can't find very many resources that discuss commissions. I assume there are some.

I did notice that some can take Credit Cards but the fees can be charged back to the owner if this service is used (usually 3%).

Are there any tactics to save on the commissions?

How long did it take you to get through the experience?

Did the Service Company offer to purchase all remaining items after the sale? At what rate?

What is the average estimate offered by the service when they come by to preview and what did you actually receive after the sale? Were they close with their original estimates?

Did you have a security service monitor the sales? How about video recording? It seems that it would be pretty easy to skim off profits from the sale before settling with the sellers.

We'd love to hear your stories...