Oh, they are definitely worthwhile. My dual wield Khajiit can kill most enemies by power attacking with both swords at once (dual wielding gives me a lot of variety, including three different standing power attacks complete with different animations and different utility: left, right and both). Since I've got the Dual Savagery perk (+50% damage bonus to dual wield power attacks) and that one perk that adds a +25% bonus to one handed standing power attack damage, I'm essentially getting a 75% bonus to my standing power attacks...and when I use both hands for one, you strike your enemy three times :toughninja:
Not only is the damage I deal outstanding, but power attacks are useful for throwing the enemy off balance, especially since I'm lightly armored, don't have a shield and focused on stamina growth. Gotta be wise about which hand to use in the middle of combat, too.
its worth it for the one-off decapitations.
On that note, I've got a problem: since getting that perk, I've noticed that the only time I get decapitations is when I kill with regular attacks, not power attacks. I've experimented a lot, and this is always the case. I never decapitate with a power attack, and only do so with regular ones. Any idea why? Also, my buddy (who is a mage) said he's decapitated enemies using his conjured swords without any one handed perks, but I don't think I decapitated anyone UNTIL I had the perk. What's going on here?