Grounding my 4 gang metal electrical box
I am not sure but I believe that would be CEC compliant.  

Another way to go, a lot of people use crimp sleeves in crowded switch boxes to save a little space.  



For this box you might do it like this:  


Wrap the receptacle cable's ground wire around a screw 
Fold all the ground wires to a point in the opposite corner 
Twist all the ground wires together and secure with a crimp ring 
Terminate ground wires on switches / receptacle grounds 


The picture below is not quite what you're doing since it's a plastic box, but it gives the general idea.  It's from this article at Fine Homebuilding.  

Although this might be more ground wire in the box, it will probably fold up better - sometimes ironically with wires too short, it's actually harder to get things folded up nice and compact.