I was born in NY, attended High School in NJ so although I was never from Philly per se, I was close, and the sandwiches I knew were usually served with provolone. Anyway, I just wanted to derail the thread a bit with a story that was relayed to me back when I was a kid. It seems that the original Restaurant ( maybe a hot dog stand I dunno) that created the Cheesesteak sold them pretty cheap. Cheap enough that a rumor began claiming that the meat was actually from a horse. The owners offered a multi-thousand dollar prize to anyone who could prove that the meat in question was anything but beef. It worked, they sold more product from people trying discredit the sandwich and never had to pay the prize. So, good move on their part. The better move was the fact that the owners started the rumor in the first place. Don't know if it's true, but it makes for a good story.
Regards,
Scam