Still....the difference in OPA between an avian hybrid and heavy is far different from the difference between an orc hybrid and an orc heavy.
For an avian just being able to double tap is enough since you will get 8 hour attack times, and just worry about not being triple tapped by the avian heavy.
But, for an orc/undead it is a world of difference of being able to double tap/triple tap/or quad tap.
At best an orc hybrid 'might' be able to triple tap, but probably not, while the orc heavy would be able to quad tap.