We weren't given a choice. It all depended upon what was needed.
Now a good 12B was the head scrounger in the team and worth his weight.
I don't know if I would have chosen commo, the way it was put was Commo or nothing.
I learned to enjoy the job. I was the "most protected" member of the team. I hope things haven't changed. We were all SF troopers who just happened to have special additional skills.