Never been to GSC Maxx, but i have been to TGV's IMAX quite a few times. The pictures were unbelievably clear, and the sound system was incredible!

But i have to say that the ticket prices are expensive. I always save them for high-octane blockbuster movies only though. The ones that have high amounts of action, special effects, and CGI scenes like Transformers or Avengers. That's where IMAX's crystal clear image projections really shine.

Normal movies are not worth it in my opinion. Unless you're filthy rich that is!