This could work, I'd suggest trying not to tie it to gold coins but instead simmulate a dematerialized system that assumes that Dwarves write down their accounts. The economy caused tons of stacks of 1 coins and killed fps. Perhaps you could mint coins and have a 'store coins in vault' job that destroys the coin stack and put that into the account.
The civil service and child care ideas are particulary nice. I'll watch this closely, this is cool.
Coins only destacked because they were physically tied to a dwarf. In the proposed system, they exist, but either have no owner, or are ALL owned by the bookkeeper. I've minted quite a few stacks of coins, and as long as they aren't destacked, I haven't had any appreciable FPS drop due to it.
Under the old economy, each dwarf started with an account of 200 coins. Coins are minted in stacks of five hundred. Thus the moment the economy kicked off, for every three dwarves, you'd end up with four separate items. 2 stacks of 200, and 2 stacks of 100 per three dwarves. Add balance flux, and here in lies the path to madness (or the old economy)
As long as all the coins are unowned, they'll only destack if you do so on the trading interface.
My thought here is you can trade your money for goods, and have a value multipler based inflation, and other stuff. Theorically, coins exist in the in-memory raws, but I suspect DF might explode into confetti if I tried messing with it; there are some memory structures one is better off leaving alone.
Today and likely tomorrow is shot as far as implementing code, and I still have to work on dwarfvet, but I'm going to try and implement the job watcher this weekend, which underpins the entire thing. If I can make that work, the rest becomes implementation details