Methinks you need to read up on economics more. Slow inflation (1-2%/year) is ideal. Metal currencies can have rapid boom bust cycles simply because the supply changes from new metal deposits. Inflation encourages people to spend money rather than hoard it, since money loses value over time. Spending money expands the economy, etc etc etc...
Inflation in-its self is a result of our economic structure and corruption nothing else. If paper was based on hard metal and the gov. controls the metal then inflation would cease to exist. Take New York State where I live. Any gold deposits in New York regardless of what property they are on, belong to the State. If no corruption occured (miners keeping ore, etc) then the state could keep inflation at 0 by expanding the supply as the population grows.
If way back in the 1500's the spanish military and privateers took all the gold right to the king, no inflation would of occured unless the king made it so. They did not do this, they kept 80% for themsleves and turned in around 20%.
And I can't remember the last time I spent 10 grand because I feared inflation, and actually my savings account bascially earns me enough interest on my money to account for recent average so I guess I'm breaking even with our current economic model.
Incorporate a corruption index, which will affect not only the economic model, but also esponage, and stability.