I haven't used Vortech to attempt to sell anything. My only experience has been as a potential buyer.
Apparently, Vortech acts as an intermediary screener between the seller and interested buyers. The ads don't give the seller's contact information directly. If a potential buyer has a question or wants additional information, he must contact Vortech.
Recently, I emailed Vortech for some additional information about an aircraft in which I was interested and wanted to arrange an inspection of it. To do that, I was told I would need to put up a deposit, an amount which was several thousand dollars and more than half the asking price. Even though I was assured the deposit was refundable, that was a show-stopper for me.
If I were a seller, perhaps Vortech might be a service I would choose if I wanted that degree of screening. Personally, I prefer a site like Barnstormers.com where buyers and sellers can interact directly.