As Longhauler stated, 9 vs 8 seats across AirTransat vs SATA. I flew on SATA last November for just the A310 rides: YYZ-PDL-YYZ. Would loved to have spent more time at PDL.

Links to personal flight pages about this roundtrip:
http://www.aeromoe.com/flightlog/flt558.html http://www.aeromoe.com/flightlog/flt559.htmlWhat would have been my first ride on the A310 with SATA, turned out to be my second flight. While hanging out in the terminal at YYZ the day before the SATA flight I booked a last minute A310 flight to Montreal on Air Transat and flew a quick roundtrip, coming back on a 737-600. Crew put me up front in Club for the short flight...which was really cool: Page about this flight:
http://www.aeromoe.com/flightlog/flt556.htmlSo, depends on where you're willing to go and if you're sitting in the rear, whether you want 8 or 9 abreast, if that matters at all.
Moe