Yamano WAS one of the biggest importer of Gibson until the late 2000. And as Dharmajester Japanese are picky on tops and quality is of utmost importance.
As for the premium, well it's given to be a tad pricier than the normal Historics or USA production, but they really kick ass in the looks category.
I got my '98 R8 w/o any COA but has emailed Gibson and confirmed it's a Yamano. The R7BB came with this (also emailed Gibson for verification):
**the SKU for Yamano is Y
LPRXXXX, whereas non Yamano will be LPRXXXX, but serial number stamped at the back of the headstock will always follow the default sequence X XXX**
By the way, both guitars were purchased and shipped from Japan.