Hi George, A friend of mine has just put his 12" G.S.O. on a EQ6.
It's a BIG package, but he finds that it balances well and it's easy to operate. Vibration is kept to a minimum. He uses it for mainly visual work, but his intention is to also use for astrophtography.
I'll get him to post a proper report, as soon as this weather clears. Cheers, John.