I can't comment on the Canopus at all. I've never even laid eyes on one let alone know what and how well it works.
The Matrox cards has it's fans, of which I'm one. however, be warned that there are those that hate it. They can be temperamental beasts if added to an existing system.
However, mine offers me render free editing of SD footage in Premiere Pro and real time export to just about all formats. e.g. I can replicate the 'neo' effect of Magic bullet in realtime on my system
Basically, it save loads of time.