Honestly, I think the average climber will be fine with either rope (except arborplex ). If you ask me, I'd say go with Tachyon simply because when the day comes that you want it spliced, the Tachyon has a much neater splice on it than the fly!

Regarding 1/2" vs. 11mm, I think emr said it well when I said he was glad he learned on 1/2", but glad he made the switch. I agree with that, but knowing what I know now, I think I would've been glad had I started with 11mm.

love
nick