Well, It would appear the op is referring to 0/40/21 vs 0/31/30.
With 40 points in combat you may want to just make it a full 41 and use the sub tree for a few pvp goodies or into assass for the pve goodies.
HARP doesn't shine quite like it used to, but that shouldn't keep you from speccing it. Hemo has okay damage, AR still has quite a kick, and Prep gives nearly unlimited CD usage. They just dont mesh like they used to.
Combat is boring and hybrids aren't nearly as good as the 41 point builds no matter what, which is where you may want to go Shadowstep. "Oh noes a frost mage! No matter. He can teleport, so can I!"
As far as comparing the two talents goes, I would assume combat potency is better seing as it is it is a tier 8 talent instead of a tier 7 talent, but thats just common sense talking, which blizzard seems to lack most of the time when designing this game...