Work well on the street in less than 6" of snow. I have never seen them on a plow truck. Constant reversing would be an issue. On-spot/Instant chain, the two manufacturers that I know, some work on electric some work on air. The trouble is getting them to work in reverse. I have not used them in 5+ years so that is my experience.
If your plowing required chains, I think you would want regular chains.
we have on spot chains on our ambulances and most of our firetrucks, they work great and are a lot of help, all of ours are electric. a great deal of help on our ambulance when getting down the small back roads.
I use onspot chains on a 1999 F350 dual wheel dump. Work great on ice. My "learning curve" was NOT to use them on rough gravel driveways. Twice I bent the arm when it dropped into a dip. Saves putting chains on 90% of the time.