For what its worth, my brother in-law owns his own engineering company (he was living in Pittsburgh at the time, close to Irwin) and worked with extrude hone on their process. I asked him about it, and all he said was "It doesnt work as good as they say it does."
Interestingly enough, I only discovered this when I saw he was sporting an "extrude Hone" coffee cup, and then I asked him where he got it, and then he filled me in.... BTW, the coffee cup is now in my posession...
I had considered getting my upper and lower done, but with the $500 cost, and his advice, I reconsidered very quickly.