Okay, this caught my imagination.
I think you really MUST combine it with performance combat, since otherwise you can't use performance feats as far as I can tell.
So where does that leave us? Pit Fighter is kinda schizo as far as classes go, but it's not really any worse than straight fighter. You miss out on a few points of to-hit from Weapon Mastery, and your feats are locked in, but you get quite a few cool tricks, and showmanship should, all things considered, more than make up for it. You even get what is basically unlimited Rage (with free rage-cycling) and everything.
Personally, I'd go with a whip. It's an interesting weapon, even though it comes with its own feat-tax. As a minor bonus, you can exchange it for the scorpion whip later free of charge (now all you need is figuring out the exact rules. maybe you don't even need EWP for it as long as you have EWP:whip, and once you hit pitfighter you can just use it normally as well? Hell if I know, see if you can persuade your DM to use the most beneficial ruling, since you'll need it).
Possible whip builds: whip is one handed, but finesse-able.
This opens up both STR and DEX builds. STR whip is perfectly fine for dealing damage, you get two handed damage bonus and everything. It has synergy with your Performance-rage too. I'd go with that as your basic build. I'll discuss DEX build later.
Now, what class to compliment it with?
First things that spring to mind:
Gladiator fighter: Gets a bonus feat that works really, REALLY well with Pit Fighter (means we can use any weapon he has proficiency with for all of its class abilities). Since we are pretty feat starved, 2 levels is probably justifyable, but I wouldn't go beyond that. Fill the rest with...
Barbarian (wild rager?): Two levels of barb gets access to rage powers (that, again, you can freely cycle). You also get a movementspeed upgrade, which is great! Wild rager gets us an extra attack as well. Plus it fills the "orc ferocity or Rage class feature" spot. Possible alternative would be Bloodrager, in this case you probably want at least 4 levels.
Warpriest: So, let me get this straight. You get 2 mini domains that you can use a bunch of times/day (War domain! It's awesome!), free weapon focus, free damage die increase for your weapon, can wear heavy, possibly free proficiency in whips, and some buff spells as swift action, and only has 1 less bonus feat than the fighter in the first 3 levels? ALL OF MY YES!
On the other hand, it rules out a number of Fighter alternate classes that you'd be interested in (Gladiator for this build, there's a bunch of others for ... here's hoping that restriction gets removed when the ACG finally hits the shelf.
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I got this far when I realised I'll probably want to write a guide for this.
