With bitcoin it's actually possible to monitor how much of your funds are left as a reserve with your bank.
If you transfer 100BTC to your bank account, and have selected a 50% CCR option, the balance of that account should never go below 50BTC.
I don't think that's true. The reserves are there for a reason...
Assume both you and I put BTC 100 into the bank. The bank invests 50 of your BTC and 50 of my BTC, 100 BTC in sum, the other 100 it keeps as reserve, so it fulfills the 50% reserve requirement.
Now I go ahead and withdraw 80 BTC. Now 30 have to come from "your account", the bank now has to liquidate some of its investments because its reserve ratio dropped below 50% (only 30 BTC for 130 deposits), but in the meanwhile (that takes some time), the reserve is used to pay me my 30 BTC. Correct?