I think the whole "efficiency" aspect is appealing. People are becoming more and more comfortable with single-engine aircraft, and add in the efficiency, simplicity, and initial costs compared to any twin, there is a market.
Right now, I feel the Meridian market is/has been dead for the last year+, but the TBM's are doing well. I'm not sure how the PC12's are holding up. It seems if you have $1mil or less, those planes are selling for us, or if you have $3mil+ those are selling well. The $1-2mil market(including used TBM's) has been silent.