What would you do if you had an endless supply of free film?
One of the big advantages of a digital camera is that taking photos becomes essentially free: you pay for the electricity to recharge the batteries and that's it. This freedom gives you tremendous possibilities to experiment and learn. OK, you also need to pay for some form of storage media (CD-R's are very cheap these days) and for the prints you make of your best shots, but if you're planning on doing your own prints from scans then you'll be doing this anyway.
Another other big advantage is that you're in complete control of the process from start to finish so you can get exactly what you want.
The snag, of course, is lack of resolution. The question to ask is just how large you want to make prints: I'd guess that, with 6MPixels, the D100 should give excellent results at A4 size and should be quite acceptable at A3.
P.S. I'm biased: I've owned a D1 for about two years....