Besides when it comes to currency i think Bisantium history is much more interesting. More intervention and more dynamic situations, not to mention there were actualy few possibility when it comes to usage of different coins.
It's come up they had in effect no usury, 1:1 gold as currency 10% tax, and an anarchic market economy with sharia law, and were very successful.
I presume there empire collapsed because the market failed as fractional reserve banking in the west allowed for capital to build a better military at the onset of WW1.