Shaping seems difficult.

[Sasquatch]

Why would you have to re-learn...

Well, a tool that does a nice job in maple may not touch briar. A finishing strategy (from first sanding to final polish) that looks "good" on maple will be a joke on briar. If you intend to take grain into consideration on you pipes (and you damn well better with maple) it's a completely different story between maple and briar. Maple will move probably 1/8" in 12" of wood with a moisture change of say, 5%. This doesn't sound like much, but a couple thousandths of an inch will make the tenon loose. Couple thou the other way and the shank will crack.

Is the basic setup the same? Yes, in that if you can drill pipe-type holes in a block of maple, you can probably do the same in a block of briar. And that is just about where the similarity ends. You can practice in maple all you like, and for basic shaping, it's not that bad of an idea. But all I can say is, when you get to briar, it will surprise you.

[smokindawg]

I also wanted to say that you need to avoid the walnut dust at all costs, especially breathing it.