It's interesting, as you admit that the current transaction system of Bitcoin is quite confusing (which it is. Any transaction fee system that cannot be explained in less words than:
"0.25c per transaction" or "0.65% per transaction" is going to appear confusing to most new users).
My hope is that, while seeming to add some complexity, a digital cash system backed in bitcoin would actually remove a lot of complexity for the average user. Much of this will be due to clever integration and streamlined UI. We shall see.
PrivateCash
PrivateCoin
BitGold
It's interesting you say BitGold, becuase in a system such as this, I would probably soundbyte bitcoin=gold, Bitcash = paper money. I do like privateCash and privateCoin. Actually I'm relly liking the word cash somewhere.
Aah yes, a certain beauty in being able to pay in 'credits'. Validates every computer game I ever played :-) We may have to issue credits backed by bitcoin just for the pleasure of paying in them :-)
So keep the track record and identity information of your client, keep it highly confidential. If the GOV want it and have the permission from the court, hand it to them. Yes, You will lose some highly private guys, but you will be welcomed by much larger group of people.
I think this is actually a good point for an additional currency backed by bitcoin - privacyInvasionCoin. Ok that was being over the top, but I think there might actually be room for a few currencies all backed in bitcoin. Let the markets sort out which.