I have IRO cranks on my SS, Sugino 75 for my Custom CX Fixie, and just got Sugino Messenger cranks in black, for my IRO build.

I haven't used them yet but according to those here who do, they are great and the price is right too- $55... Matching them up with the Messenger chainring and I'm good to go.

The S75 are just awesome.

You can go low-end, mid-range or high-end.

You can't go wrong with the Sugino Messenger Crankset. About $115. You can just look at them and tell they are better than the Truvativ.