I'll try to answer your question, from an amateur's view:
A gold-only standard would be the same as a fiat money standard, except with a limitation on inflation.
True. The theoretical danger with a gold standard that I posited was the opposite: deflation, high interest rates and massive unemployment brought about by *too little* a money supply. My question that remains unanswered:
What free market mechanism(s) would prevent cartels and monopolies from arising that artificially constrict the gold supply?
Which one is more dastardly? A banking system hoarding gold (and putting itself out of business in the process if it takes it all out of circulation),
How easily you forget history, Americans have railed against a pure gold standard in the past and blamed "foreign bankers" for constricting the gold money supply. This made life extremely difficult for businesses who owed banks money. Falling prices meant lower income for businesses, which means less money with which to pay the bank's interest. And if businesses are unable to pay the interest, foreclosure results:
See
http://en.wikipedia.org/wiki/Bimetallism,
http://en.wikipedia.org/wiki/Coinage_Act_of_1873 and
http://en.wikipedia.org/wiki/Panic_of_1893
I'll add to that my opinion that the government's constitutional role in all this is to maintain a standard of weights and measures. The constitution allows states to make their own coins, as long as they are of gold and silver.
Of course the problem of bimetallism crops up again. What is the proper ratio between gold and silver? The answer is the government cannot/should not set such a ratio and would instead have to let supply and demand set it.
Why so? Because if the government made silver and gold coins that, for example are worth 25 cents (silver) and 5 dollars (gold) respectively, for a ratio of 1:20, when gold prices are above 20x silver, people will be encouraged to hide (or melt) their gold dollars and the economy will effectively move towards monometallism. Gresham's Law - "bad money drives out good". This *has* happened in the past.
This is why the most conservative step that can be taken is merely to remove capital gains taxes on holding of gold and silver and not necessarily create gold/silver coins or even back FRNs with silver/gold. Untaxed gold/silver transactions would act as a warning canary for when the Fed inflates the money supply. This, of course, already occurs today, but taxes add a fair bit of 'friction' to the process.
Debt instruments can be and are traded as money, and if the terms are better than borrowing gold at interest, who would borrow gold?
FRNs can be thought of as debt instruments, but due to fractional lending, grossly inflated ones.
Why can FRNs be loosely considered as "debt instruments"?
First of all, contrary to any misrepresentations that you may have heard,
the Fed does not create money 'at will'.
Money is created when banks or the government borrow from the Fed, hence 'debt-based money'. The Fed lends to the banks presumably with the bank's assets as collateral and to the government presumably with the nation's assets (incl. taxes) as 'collateral'.
Stop the government from borrowing too much from the Fed and you will have removed much of the impetus for the creation of new money.
The
real power of the Fed is in setting interest rates. The Fed cannot increase the money supply if no one borrows from them, *however*, if it sets interest rates at a very low level, it would encourage a lot of borrowing and *this* is what will possibly lead to an inflated money supply. Throw in situations where the Fed engineers bailouts of financial institutions that are deemed 'too big to fail' by 'injecting liquidity' or by aggressively lowering interest rates and you get your recipe for inflation.
On the other question, as to whether other countries' fiat money could drain gold reserves (whose reserves?). Only if the gold were traded for the fiat currency at a fixed rate. Why would you sell your gold for paper that falls in value?
I'm thinking of the situation wherein USD notes are redeemable for (e.g. backed by) gold but other countries' currencies aren't. Example: The US imports from China and pays for it with gold-backed USDs. China can then opt to either spend its USDs by buying US assets or can exchange it for gold. Now, if the yuan weren't redeemable for gold, the gold flow would essentially be one-way.