Thanks J-Guy. In fact I've just tried again on their website & it now shows the GCI-STN flight as well. I assume it was just a glitch on their site earlier this morning.
Regarding demand, if the price is right (especially this summer) then it will be a success! They have lots of experience vs. FlyBe on this matter & in my experience they're a lot less hassle as you don't have to pay extras etc.