=Today's System=
Today money is a commodity supplied out of the void without any qualitative differentiation across a market based on debt and violence, and the ones who first touch it wins all because new money destroys every price it meets. You can dream about it like black goo being pumped from darkness and darkening everything it touches.
I really like this visualization. It captures the essence of the matter better than any other I have heard.
1) in terms of behavior selection and group survival: thieves, liars, lazy and inefficient people gonna be rapidly determined as dead weight and dropped from reputation groups and by users that can trade most sophisticated goods, also peer pressure will act locally and non-locally in a way that they mend themselves, lessening the cost of free-riding/laziness/dishonesty. This behavior selection would escalate by the club good nature of life. So if you trade reputation inadvertently with unknown people, without even testing it with a trade, you are gaining little reputation while sending a bad signal of confidence to all the people who trust you
I can see this as being useful for small groups and local communities as a way to reinforce community bonds and build wealth. Technology can probably enhance the number of people you can realistically keep track of to a few hundred. However, I am much less confident this can scale up like you are envisioning. Once you grow beyond a size where you can keep track of the individuals involved you become reliant on a large centralized reputation system and that is inherently prone to abuse in several ways.
Potential Problems:
1) Individuals who game the system acting honestly with multiple small local trades then comitting fraud on rare large trades with distant individuals.
2) Use of a centralized ejection mechanism (being kicked from the group) as a tool for unfair wealth extraction/terror of low power individuals.
3) As the system grows it will become vunerable to the same difficulties our current system faces. (Outlined below in the Iron Law of Political Economics Quote).
4) Who pays for development upkeep and maintence of the system.
Some Iron Laws of Political Economics
Political demand for income transfers, entitlements and subsidies always rises faster than the economy can generate increased wealth to supply them from.
Although some taxes genuinely begin by being levied for the benefit of the taxed, all taxes end up being levied for the benefit of the political class.
The equilibrium state of a regulatory agency is to have been captured by the entities it is supposed to regulate.
The probability that the actual effects of a political agency or program will bear any relationship to the intentions under which it was designed falls exponentially with the amount of time since it was founded.
The only important class distinction in any advanced democracy is between those who are net producers of tax revenues and those who are net consumers of them.
Corruption is not the exceptional condition of politics, it is the normal one.