Yeah, as greenberet said in the FI thread,the ethanol can corrode certain grades of aluminium, which is why some manufacturers won't certify their legacy engines as ethanol friendly. The two major components affected are the rubber parts in the fuel system and the aluminum components that come into contact with the ethanol. The rubber parts are easily remedied, as you can just offer a retrofit kit with tougher gaskets and o-rings. The problem is the aluminum. Thankfully, the C30B has iron sleeves, which avoids some of the problem. But, the heads are aluminum and I don't think Honda has said whether the particular alloy used is ethanol resistant. They stopped making the NSX in 2005, so I doubt they've even tested or considered it for this engine.
Still, assuming the heads check out, I would consider this mod somewhere down the road, especially if I go FI. I get to pick up a few hp and pollute less...not a bad deal imho.