Douglas;
Yes, Alder would make good charcoal also. For me it's a matter of finding a sustainable local source and Willow is plentiful. Since I have the process "down pat" for the Willow I'll continue to use it. Others will probably want to search locally for good wood.
I don't try to duplicate GOEX or Swiss but rather make a consistent powder that my be faster or slower, as long as I can produce a consistent powder, I'm happy. This would include screen size, I don't try to replicate the exact size of commercial powder but rather get a consistent size.
Bill