This is an opinion that I've been wanting to express after watching some of the recent fights but I've been waiting for the end of the arc to evalute it as a whole, but I'll share it now…
This (most likely) conclusion to an otherwise awesome arc has let me rather dissappointed, but before I start on why, I'll also add that before the start of the fights my idea was that the Mugiwara wouldn't be able to defeat every one of the CP9, and that it would end in a parcial victory of some sort (like getting Robin back and CP9 having to retreat, and the Buster Call would have been the perfect excuse for that).
My reasoning for the CP9 being that good: Kamie, Soru and their ruthlessness. And what do we get now that the're fighting? The CP9 hardly use kamie, they don't overwhelm the Mugiwara with soru, and they spend too much time being... Goofy rather than being ruthless. I know that the goofyness is what makes One Piece unique, yet I think Oda went overboard on this one. For example, the battle between Luffy and Blueno was... Perfect. Kalifa against Nami? Didn't make sense, at all. What is Kalifa waiting to just go Soru on Nami? Why waste time using her DF powers? And please someone explain how did Sogeking and Zoro managed to escape Kaku and Jyabura for so long... Soru anyone?!?!
The fights are just too convenient, the CP9 abuse Geppou, Tekkai and Rankyaku, yet kamie and soru that would make the difference they hardly use them (for example, when they use soru they usually hit the manuever, and the few times kamie was used they never were hit).
The start/middle part of this arc was awesome, yet if this really is the end of the arc... It's still good, but nowhere near the quality of the start/middle part of the arc.
So, after watching the fights I come to the conclusion that OP is still bound to the rules of shounen manga, so I say Luffy will win (Please prove me wrong Oda!!!! :) ).