Since Drew Karpyshyn is evasive in regards to direct comparisons between characters, I manipulated the context in such a way as to get a pretty solid answer from him. This is an email I sent to him not too long ago:
"So, a character in the star wars universe that has always intrigued me is Emperor Vitiate, the main antagonist of Revan, as well as the Star Wars: The Old Republic MMO. From how he is depicted in your novel, he strikes me as a being similar to Darth Sidious in control and appearance, but at the core he is far madder, nihilistic, even more powerful. He seems to have transcended both jedi and sith, rather becoming an entity of unimaginable strength. When Revan fights him, it not only seems like the greatest opponent he's ever faced, but rather the greatest opponent anyone has ever faced. My question to you: Was this how you imagined the Emperor when you wrote your novel? A godlike abomination bent on destroying the galaxy to become even more powerful? Because from implications on his backstory, it seems that he's already transcended all jedi and sith, from any era. Thanks."
In this email, I fellate the Emperor to the extent where it couldn't be ignored in response. To be exact:
"I didn't actually create the Emperor; the SWTOR online team had fleshed
out much of his character and backstory before I came on the project.
However, I think your analysis of his character is pretty solid - that's
sort of what I was going for in the novel. The only thing I'd add is that
he's also very insecure: he has immortal power, and he's terrified of
losing it. It's sort of ironic, because the stronger he gets the more
desperate he becomes to hold onto his power."
So yeah, take it as you will. I just thought it was pretty interesting.
So he finally answered you. Quite interesting that he approved your depiction. You basically made him indirectly say that Vitiate is more powerful than FOTJ Luke.
I'm not sure what to take from his answer.
Seriously, he is being described as a godlike being yet has so few showings and his almost impossible to achieve feats like DC one-shoting or Natemha annihilation seems to have required prep. I think the closest we get to see his real powers in combat are in Revan and his performance against the Jedi strike team on his space station which are pretty insane as well but I would love to see more.
I love how Karpyshyn's so quick to mention that Viti's afraid of losing his power like it's some sort of unique, unprecedented aspect of a Star Wars character that makes this particular one all the more special.
"YEAH HE'S SO UBERLY POWERFUL AND AWESOME AND EPIC HE'S THIS TOTALLY NEW THING A BLACK-CLOAKED EMPEROR OBSESSED WITH ULTIMATE POWAH BUT I DID THIS REALLY COOL THING WHERE I WROTE HIM AS INSECURE BECAUSE HE LIKE TOTALLY LIKES POWER AND DOESNT WANNA LOSE IT ISNT THAT COOL?"