First off, congrats!!! I hope you have a healthy and uneventful pregnancy.
Both hospitals have excellent reputations, that's for sure. I don't have personal experience with either, other than my mom giving birth to me at Hershey almost 30 years ago at 28 weeks gestation. I know I received the best care around and am fully normal and functioning now.
A friend of mine had pre-e and was on bedrest for a few weeks at Harrisburg then gave birth to her son around 34 weeks, I think. She had a positive experience there from what I can remember.
For what it's worth, I did a ride-along with Life Lion in 2009 and one crew member remarked how mothers on bedrest typically go to Harrisburg, while new preemies typically are flown to Hershey.
I can understand your hesitation about switching practices, but if I was in your shoes I would pick Hershey, hands down. Everything is already there and you wouldn't have to worry about you or the babies having to be transferred somewhere else.