Yep. Perhaps you should read this article. I think the iPad will be very hard to displace in the medical field, and your HIPAA concerns are easily addressable. Doctors will want the same great experience as they've had with their personal iPads, and Win8 is unlikely to deliver.
Read the articles and worked with a dozen healthcare IT shops trying to figure out a way to make it compliant.
You can lock it down to a browser only based tool, but you can’t do the rest.
“My HIPAA” concerns are those of the doctors who don’t want to pay a few million dollars when their patients data ends up somewhere it shouldn’t be. At least thats what they tell me.