If you have to think too much during a raid you will most likely fail on mechanics, so just go slowly with it, but meta isn't really that hard just HoG -> 2x shadow bolts or 1 shadow bolt 2 instant casts (you can also fit in 3x Soul Fires with the 8097 haste breakpoint) -> HoG and go into meta, without any haste procs that is. if u got meta just add in 1 more cast after first HoG. That's atleast what I go after.
Btw, just a question. Anyone that knows of any exact "haste breakpoints" when it comes to the metaweave, like at what haste u can fit in how many casts of spell before 2nd HoG cast? I was thinking that those breakpoints might give small dps boosts if any existed.