I'm interested in this function as well. I'd like to try to analyze his script to see if there is such a bound, or at least some theoretical results to be pulled out of it, but I didn't see the guy's script on the page; has anyone found it?
The page http://www.benjoffe.com/holdem_files/heuristic.html is running the two-player case. It seems to be using a Javascript hill-climbing algorithm: pick a scoring function which measures how good the solution is, then start from a random deck and try small changes, keeping them only if the score improves.