I think Heracross would be way too beastly in UU. Rhyperior is more of just a pure offensive juggernaut, but it suffers from very common 4x and 2x weaknesses while also being slower than frickin' Hariyama.
Heracross, on the other hand, has pretty great typing, and out speeds the common base 80's in the tier. he can also "bring the pain" well enough, off of his tremendous attack and dual 120bp stabs.
I just feel that Hera's combination of speed, power, and relative decent survivability(solid special bulk, especially) would be too much for most of UU to handle, whereas Rhyperior can be checked well enough with most teams, via standard moves such as EQ, Aqua Jet, grass attacks, low kick, etc.