I have one of those koa / spruce GS's from 2006, bought used. It sang to me starting with the first chord, and I took it home an hour later. It is my best guitar, period. You would enjoy it. Mine is NOT for sale, and will be the last guitar left in the estate when that day comes.
I also got my 424 LTD all-koa GA from Martin Music, and the transaction went superbly. Highly recommended folks.