Your fear is unfounded, Heinz is a great atmosphere for CFB. I have only seen it get rowdy for WVU and that was when they all started chanting eat $hit pitt. There will not be more of you guys than Pitt fans though-- you will have 20k tops...relax and enjoy the game, honestly one of the more laid back places to watch a cfb game, most of our fans are older and there will be a bunch of families with kids on hand. We dont have 40k drunken undergrads in our stadium, for better or for worse. Come to Pittsburgh, eat Primantis, go to the museums, tour a real college campus, and revel in enjoying the return of one of the best rivalry games in cfb. Hail to Pitt.
The fact that your fans will be older is what would worry me. I've been to one Steelers game and will never go back and it was the "older" fans that were the problem. It was not a great atmosphere for a pro game so I seriously doubt it's a great atmosphere for a college game, especially with Penn State coming to town. This one will make our road trip to Rutgers look like a welcome home party. Only Pitt fans actually think their fans will be well behaved.