To me it seems like Improved Concussive would be more useful than either Efficiency or Improved Mark. Now my last hunter was MM spec but this was pre-TBC, and I'm debating between MM or BM for this new one (I'm coming back after a 2 year break).
Obviously this will be pre-70, and while I plan on dabbling in a little BG and will be playing on a PvP server, most of what I'm going to be doing is soloing and instances. I know my end-game spec already.
Basically I'm asking why nobody seems to get Imp. Concussive, even in PvE it seems like it'd be handy and I remember using Conc a lot if my pet dies or if I get adds. Is it not as effective as it sounds? Does 20% just not proc as often as it seems?
If I spec'd BM, Imp. HMark would help my pet's damage, right? So is that an obvious choice if I decide to go BM? And maybe Imp Conc if I go MM? Or would Efficiency for mana problems be more helpful to a MM spec?