There's a big difference between medium and large format. Not the obvious one ;) , but the fact that large format (4" x 5" and larger) cameras generally have "movements". This way you can alter the perspective of your subject. One example would be to keep a building from looking like it's falling away from you just because the camera's tilted up. You can also change the amount of depth of field.

If you need the control of a large format camera, you're probably best to shoot film and scan it. Scanning backs for LF are available but I don't know anything about them other than they're extremely expensive and take long exposure times. I think they kind of work like a flatbed scanner works - that's why the exposure has to be so long. Probably limited to studio product or architectural photography because of this.

I read recently that Hasselblad came out with a digital-only version of their fairly new H1 system. That's a lot of money to spend on something that's not as versatile as a MF SLR with a digital back, so you can still shoot film. Most systems (like Hasselblad, Mamiya) have digital backs available.