Hey Strummer,
I'd go back there, grab both and one guitar stand, and go back and forth. Seriously spend time with em. It's a significant investment, both monetarily as well as emotionally. As Dennis said, new gets
you the lifetime warranty which is good, but not "enough" a perk if your gut, fingers, and ears gravitate toward the used. And the Koa always has "its thing" going on with its own sonic character, and of course the beauty of the wood, not to mention the benefit of having a few years under its belt which to me is an excellent trait! I love the Gotohs, but that's $100 upgrade you can put on any guitar. And a "deluxe" case means nothing to me.
Yup, go back and claim both (so no one takes it) and sit and play
for a while. With more time, no rush, you'll feel yourself tipping toward one of them.

Edward