I have gone back and forth about this many times. The part with Shawn yelling "God damnit, Vince" was unquestionably an act (either for the show or to Bret himself). That point can't be argued since he admitted he was in on it.
I do have to agree that if something was going to come out regarding it being a work, it probably would have been done by now. Being in this day and age, it is extremely difficult to keep information private due to the Internet, I'd be surprised if it was a well-kept secret for this long.
I also was told the Undertaker story from friends of ours that work for the company. Taker basically demanded Vince apologize to Bret for his dishonesty.
Unfortunately, taking the point that this was a shoot, I still do NOT stick up for Bret. Bret obviously thought he was bigger than he was. He has no right saying that he doesn't want to lose in Canada because it is his home. What if Michaels was champ? Should he say that he "doesn't want to lose in the United States since this is his home, too"? Vince knew Bischoff would throw a lot of money at Hart to go on Nitro and do the same thing Madusa did, as Nitro was gaining a ton of momentum during this time. He couldn't take the risk.
I do believe Vince was hit, but I wouldn't be surprised if makeup was used to embelish his injuries for the camera. It's the wrestling business. Not a business for honest people.