I use them for a load of my .coms and it's all a bit confusing to be honest. I haven't had a sale yet ( in 12 months ) but I keep getting emails saying update your price for "X" domain as we have an interested party...so I go in and update the price and the next day I get update price etc etc?
Eventually I'll get an email saying if you don't sort it we'll remove the domain.....go figure as they would say
Sound like more of a moan than an answer to your question I know...sorry
I have never sold a domain through Afternic or any of their affiliated websites. I guess there's no harm in listing your domains on there for the added exposure, just don't expect too much in the way of money inflow.