Nihilus is a damn wound in the force, so he is more powerful than anybody who doesn't have a defense for it(which is everybody but the ancient sith), and anybody who can loop in and out of the force(NJO jedi).
I believe DE Sidious can loop in and out of the force, or rather move faster than the eye could see, so Nihilus would be sliced in pieces before he "ate" him.
I seriously don't get all the hype about N's drain. Why can't it just be blocked? I've kinda gotten the impression that there's a load of mixed up speculation going on here, but really, when does KotOR say that his drain is anything as special as people make out? And Sexy, please elaborate. You've noticed I've said that to you a lot recently, it's kind of because I suspect you're just parroting Lightsnake and other members and don't actually have any clue what you're talking about. [SPOILER - highlight to read]: No offense intended.
DE Sidious could do it at any point in time, we saw Bane do it ONCE and ONLY once against Kas'im, and Kas'im countered it. It is very unlikely Bane has the force mastery of Sidious, to defeat Nihilus before Nihilus eats him.
Bias...
We only ever see Sidious do it once as well, and just because Bane was only noted to have done it once, it doesn't mean he can't do it whenever he wants to.
Bias? How about DE Sidious was miles ahead of every other sith lord with virtually every technique under his belt? But according to the great debater that you claim you are, facts=bias.
No. We see both characters display that kind of speed once, yet you highlight the fact that Bane only did it once, whereas with Sidious, you say 'he can do it whenever he wants'. That's clear bias...
Who in hell Nihilus kills an entire planet of force sensitives plus hundreds of jedis with 1 single attack? And "wound in the force"? Kotor II just changed and twisted all the concepts from Sar Wars world...
Anyway, with such condition Nihiilus wins. In fact he will always win this way...