Reason i said no, it would require a rework of most of the class abilities. I mean for the commando, need the assault cannon to do most of them like grav round, or charged bolts.
Use anything else, most abilities don't work.
Reason why i don't think it's a good idea. Novel and inventive, but with game mechanics, just unworkable.
In the proposed idea, if you swapped to the mirror side, the abilities would all require dual pistols where they had previously required assault cannon.
I think it's a great idea.
It would require minimal (if any) balancing to make work correctly.