I see one advantage in this setup, and several weaknesses.

Advantage: The ability to send fiat currency quickly to anywhere in the world assuming you have a network of 'fiat bankers'.

Weaknesses:  The Bitcoin protocol was brilliantly designed to solve the problem of incentive to secure the network, with the reward being some of the value from the network.  By unlinking the two, there is no incentive for securing the network (mining).   The other weakness is that you have security risk with the fiat bankers which you may solve, but it is very similar to the risk that exchanges pose at the moment.

The primary problem you seem to be solving is the volatility, and that can be solved more easily by having many exchanges like Coinbase, BTC-e, Bitstamp, and bitcoin ATMs.

If you don't want the volatility, hold fiat.  When you need to send value  -- Exchange to bitcoin, send, and let the receiver of the value decide whether to transfer back to fiat, or hold the value in bitcoin. 

Fiat and bitcoin (the currency/commodity) both have risk.  Ignoring any security issues for the moment, fiat can be 'quantitatively eased' to a lower value (reduced purchasing power), while bitcoin currently has extreme volatility and the value goes up and down based on the news of the day.

Tron
Founder, CoinCPA