I thought Globespan and Air Transit are one and the same.
Here's a uk review: [broken link removed]
I booked a trip with them for the inlaws a few years ago to Toronto.
The reports I got back were that there were a trans-atlantic version of Ryanair alright but you get what you pay for ! Got great value (less than €400 return Dub / Toronto and my understanding was that it was the main Toronto airport. The only real complaint on board was the leg room for such a long flight !