Gypsy -

Every piece of wood is a little different, so it's up to the luthier to make the piece he has do what he wants. There is no real reason that a good luthier shouldn't be able to use koi (a really broad generic name for a whole buch of woods) to make a decent mandolin.

Particularly for an "F-Style," where "resonance" is not usually emphasized, you should be able, within reason, to get good results with almost any "pretty" wood.

For an "A-style," it's common to put more emphasis on getting a good "resonance" - what some call a "lutey" sound, and if that's your choice I'd have a long talk with the luthier before using anything but a top-grade spruce top.

In a guitar, the characteristics of the wood can be compensated by "trimming" the bracing; but mando tops are not significantly braced (with some exceptions) so that all the "compensating" has to be done in the wood itself. It's much more of a "what you got is what you get" situation, unless your luthier truly "works to the wood."

Consider also that by the time you put a pick guard on it, and get it into playing position, very little "mandolin" is going to be visible, so there is much less opportunity to "show off" a fine piece of exotic wood - and it doesn't make much sense to sacrifice tone and extra money for something that doesn't show.

The bottom line is that you need to decide what your priorities are, (tone, action, loudness, cost, & pretty?) and talk to the luthier who is going to make it before he goes to work. Every instrument is a compromise - you should consciously chose which ones to make, with due consideration to what your luthier recommends.

John