Rainer,
If you can get it cheap, and can live with tethering to a computer, go for it. It's not too long ago that pros were using the H series. Many pros still tether their P45s, whether it's on location or in the studio. And you can still use it on a view camera and stitch away. Sure, it's more work. But right now, that's okay, I guess.
Yes, you need to get a medium format body and lenses. But look at they are going for these days. A full set of 2 Mamiya bodies and 4 lenses sold on this forum for the princely sum of $800! Get a compatible Mamiya, and you're set.
If you like what you see, keep it until you get a larger chipped back, or simply use it as a backup.
It would be a small investment to make before you spend a heap of money. Even better, rent one for a couple of days, if possible.
Cheers,
Kumar