frost is the way to go right now sadly, its more damage and you dont gain anything by going unholy really.
MOP and Cata version I agree it would be too strong since the absorbs were retarded and there was a casting speed debuff which is not needed. However a 10-15k absorb per strike even in the current meta would hardly be OP and it would still be better than Scourge Strike which does 5k on plate. Scourge strike is something Blizz cannot make stronger because PVE.
Would also help protect Soul Reaper which only crits for 30k while my hunter partner does instant 45k Killshots with no resource or CD.
And I am only taking about Unholy 3s since both 2s and even duels we seem to be fine. However in 3s, Frost seems to be all out better even with Shadowcleave which is supposed to be an Unholy Comp.