I think 100% reserve is too much.
I would be much more comfortable with 50% reserve.
As for the temporary cap on the NuBits money supply, I understand why you d want to set it. Because you want to limit Nu’s liabilities as long as the peg is not restored.
But in any case, the reserve ratio question’s answer depends on the following question, I believe: Do we really want to still peg via NBT/BTC only?
I think this time we really need to develop ways to peg via NBT/USD too.
Maybe we can start with 50% peg via NBT/BTC 1), 50% peg via NBT/USD 2).
In each case, the necessary ratio of reserve should be different.
2) ratio should be typically much lower than 1) ratio since 2) is not exposed to BTC volatility.
As for the cap, in case we find ways to get revenues (and I think this time we must do so) (ex: NuCost API, some kind of burning mechanism to make NuBits holders pay for the privilege of using NuBits), probably we would not need to set a cap because the NuBits destruction would counterbalance the inflation, though I feel it would be safer to do so at the beginning, in any case.