"A currency that doesn't grow will be naturally replaced by one that does." seems right, as long as the minimal discrete value of the currency that doesn't grow cause a problem for the economy.

But if you can move from discrete to continuous space (bitcoins can be cut up to 1E-8, and according to what I've read this is not a fixed limit), why bother moving to the other currency ?

(I hope I get it right - it's an area I don't fully understand)