When I moved to the gateway, it was to replace a PT sup that they wanted to send driving with the intention of promoting them to FT sup (not specifically on-car). She ended up signing a union card and basically giving upper management the middle finger. Now in my case, which was about 7 years later, they had procedures in place to make sure we didn't get enough time in that particular spot in order to be able to do the same. I believe I got 29 days in total before they brought be back to the gateway....still as a PT sup.
As far as the OP's original question....PT sup is probably one of the toughest management positions in the company. If you lack thick skin and mental toughness, then walk away. If you lack social skills or people skills, please don't add to the vast amounts of management that need not be in charge of humans. As far as opportunity goes....it's nothing like it used to be. PT supervision is basically a 'hold-over' job until you find something better somwhere else....whereas before it was a platform to spring your advancement through the company. This is no longer the case. If you are even the slightest bit inclined to be a driver...just stick with that. The same potential advancement in management can come from being a driver, all the while making much better money and benefits. I'm still predicting that PT sups will one-day unionize....