I have about two hundred photos there and i got only one sale in two years. My experience with that site is
1) composite photos especially with aircraft ones are quite popular
2) looks like they favour same artists and photogs
3) if you have not got anything british related (landmark,architecture etc.) don't bother to upload.
4) they have a new web site template, with the old one there was a forum where you can communicate with other photog and artist
5) i guess one person manages the website