Its really all personal preference. You sound like youve made up your mind tho on the Ar6s. If you want 166 then get the 166. I feel that if your going to centermount them and use them as your park ski, get the 176 or 171, but thats just me. As for the seths, thats a tough one. Seems like your right on the cusp.
"So I jump ship in Hong Kong and make my way over to Tibet, and I get on as a looper at a course over in the Himalayas. A looper, you know, a caddy, a looper, a jock. So, I tell them I'm a pro jock, and who do you think they give me? The Dalai Lama, himself. Twelfth son of the Lama. The flowing robes, the grace, bald... striking. So, I'm on the first tee with him. I give him the driver. He hauls off and whacks one - big hitter, the Lama - long, into a ten-thousand foot crevasse"