De - excellent post, with two exceptions.
Nixon DID have a choice. He could have changed the exchange rate (still a massive devaluation of currency) by going to a floating exchange rate equivalent to the prevailing market price of gold.
Second - YES - productivity gains against currency inflation DO result in prices remaining the same. The problem with this argument is obvious. WITHOUT inflation, Productivity gains would result in DECREASING PRICES. Ergo: Inflation HAS increased, devaluing the value of currency, and price inflation HAS actually occurred, but it is obscured by the
'price remaining the same'.
Mises was 100% correct in his analysis.