Borbarad
Advocatus Diaboli
Hmm...
I would say DN Luke would get at least to Sadow or he makes it all the way through. If you want feats put into context:
a)
In the scene were Luke gets attacked by Kun's spirit and Kyp Durron in the Jedi Academy trilogy, Anderson states that Luke would have been able to defeat both Kun and Kyp if only one of them would have attacked him. So Luke 20 years before DN was superior to Kun's spirit. This is why Kun never attacked Luke alone - and we're talking about Kun's spirit who still fried one of Luke's students, knocked another one off without effort and force choked the entirety of Luke's students at once.
Even while I agree that a living Kun would be stronger than his spirit I fail to see why Luke - who is superior to Kun's spirit - shouldn't be able to take the living Kun with additional 20 years of training and experience.
b)
The fight against the Vong is a good example for Luke's combat abilities. He moves so fast that even trained Jedi can't follow his physical movements any longer. Even if Jaina's thoughts here are a hyperbole ("seems as if he was wielding 20 lightsabers at once", "unstoppable"😉 he must have been unbelieveable fast.
Than he just rips through 7 slayers as if they were nothing. Kyp Durron - who isn't a weakling exactly - had problems with a single slayer. Luke killed 7 without much effort after cutting his way to what seemed to be an army of Yuuzhan Vong. And his "emerald lightning instakill" (which was in fact an instakill as Faunus has corrected my own view of that scene) was used against a being that should have been immune to the said effect. That even trumps instakilling a force user - something compareable would be using the mind-trick on Jabba. It simply shouldn't work - yet it did.
c)
The DN / JA-trilogy situation I've mentioned. The combined power of Luke's student was enough to force push a star-destroyer out of the Yavin system. It took the combined power of more Jedi with better training and more experience to block one of Raynar's attacks while Luke blocked the same thing on his own.
I know that the amount of force power Raynar was wielding isn't exactly quantifiyable - but still that entire situation is grotesque if you suggest that Luke's own force power is on par or even above the combined power of dozens of his students. Especially thinking about the fact that the combined power of several individuals appears to be greater than their individual powers added (that's what it looks like when Luke's students together could force push a stardestroyer...)
d)
While Kun is one of my favourite characters - or even my favourite one (Look at my signature - he isn't there without any reason) I believe he's overrated here nowadays. Maybe because of what Janus calls the "anti Kun faction" or maybe because IKC just wants him to be uber-powerful.
Sure Kun is a lightsaber prodigy. We don't have to argue about that. On the other hand Kun didn't have too much training to perfect his skills. We know that Mace Windu is a lightsaber prodigy (anybody want to argue that ?) but even with nearly 5 decades of training he wasn't able to beat Yoda. Dooku was a master of form II - possibly using that style for 80 years. Also not able to defeat Yoda in a lightsaber duel. Now Luke in DE fought a person that gave both Yoda and Mace a pretty nice fight and Luke won. And he did that without much lightsaber vs lightsaber combat experience. Now I fail to see how 20 years filled with lightsaber vs lightsaber combat and force training added to somebody who already had a lightsaber skill that was above the ones of Obi-Wan or Anakin (or on par with Yoda, Mace, Dooku) would make him less skilled than somebody like Kun. Just because Kun has beaten Vodo who's fighting skills are great without a doubt but we can't say he's better than Yoda or Dooku or somebody else ? A little bit too much for my personal taste...
Then Kun has killed Odan using the force. Odan had attacked Kun with a great amount of his power before and was weakend by age (put it like you want but that was clearly the case). What makes you think that Kun can reproduce that action against somebody who appears to be quite more powerful compared to Odan, is in a better physical condition and has already shown the ability to block rediculous powerful force attacks ? I don't see it...
While on the other handside Luke used some instakill on a being which - theoretically - should have been completely immune against force attacks.
So what has Kun left. His "freezing" ability ? He never demonstrated that against force users. "Controlling others" - again never demonstrated against force users and I think that both things would have been pretty useful when he was confronting Ulic and Aleema, Vodo, Odan or basically anybody he met. Especially Kun who likes to toy with his enemies wouldn't have let a chance pass to demonstrate his vast superiority - or would he ?
Now the only thing we have is Kun's amulet. He even said himself that he wasn't nearly able to control the blasts coming from that amulet - and - suggesting IKC is right - he never used it to blast another force user. Why not ? At least I fail to see why Kun should be able to use it precisely against somebody moving as fast as Luke can or why it should have any great effect on a person able to block (or "turn away"😉 fire from a stardestroyer and an AT-AT as well as massive force attacks. I even fail to see how Exar would be able to use the amulet while fighting if he can only hardly control the power of the amulets blasts.
So, yes, I fail to see how Kun would be able to defeat DN Luke. Normally even NJO Luke should be able to defeat him - redicously overpowered as NJO Luke is.
And Sadow...well...I don't know. Given that Kun used quite much of Sadow's own knowledge while Sadow has never demonstrated any real combat ability I'm used to suggest that DN Luke might even have that fight (which would be damn hard anyway).
At least I fail to see how Sadow should "kick Luke's ass". That surely won't happen.