based on my experience...those Ipanema tires are good on prepared race tracks only..if your racing at very hi-speeds the foams are the way to go,they wont baloon and they run true so they are pretty much balanced and stable compared to rubber and foam distortion at hi-speeds,the hotter the foams gets the grippier and softer they get,you just have to keep them clean.
again this is based on my experience using both ipanema and ofna foams on my heavily modified ofna gtp2.