I haven't looked at your glyphs, but simply looking at your profile, gear and stats I would say bump haste down to the 1235-1250 range. You might be able to come out much more on mastery and even a bit ahead on your crit. See if you can lower down to 961 hit rating too (8%).
Largely, later on haste becomes much more viable, but this will be dependant on high lvl gear and trinkets (hungerer, matrix restab). So with a arc shot focus dump rotation it might prove to be more useful to have more mastery to fill in more auto shots = higher dps. Later on Aim shot focus dump can be better (esp in tank/spank fights).
Personally for me I'm waiting until I get a few more upgrades before trying out the Aim shot rotation. ( I wanna see 30% or better crit and mastery still in the 14-15 range that will be unaffected by adding back more haste)