I'm curious about how you use 500s to play poker. Don't all the odds change for each poker hand? If you did the math, can you share?
They're not really used much for poker. As I'm sure you know, "500" decks typically have values of 11 and 12 in all four suits, and some have values of 13 in one suit of each color, typically spades and hearts. (This is all in addition to the usual set of courts, not as replacements.) They're used primarily for playing games of rummy, gin rummy or rummy 500 with up to six players instead of the usual limit of four - it is thought of as a better alternative to using a double deck, which in rummy makes many card combinations too easy to obtain.
As far as playing poker, I'm guessing with a little "napkin math" that most combinations would be about as difficult to obtain with the exception of flushes, which would become easier, I think. Persi Diaconis
would be the better man to ask!