I've been prioritising Exo over HoW since 4.3 hit because HoW is no longer (pretty much) an auto crit.
The current CLCret rotation on EJ (
http://elitistjerks.com/f76/t53171-r...1/#post2057749) also has Exo prioritised higher.
The only time I use HoW instead of Exo is if the dot from the Exo glyph is already on the target.
Just ran it through simcraft using my character (armory link is in my sig)
self buffed, patchwerk fight @ 50,000 iterations. Note: it puts Exo ahead of HoW by default *hint hint*.
Exo>HoW = 25029 DPS
HoW>Exo = 24977 DPS