> shove surplus into gold/bitcoin/stocks

That's just one version of the subsequent exchange that I'm talking about though. If the value were falling so quickly that you couldn't get a sufficient amount of gold/bitcoin/stocks, then people would stop using the currency as a MoE.

> we accept something as MoE because it's value stores long enough to exchange it for something else of similar value.
hm... I don't actually think it matters. Both equilibria work: 

1) produce for money, hold money the PP of which appreciates (like bitcoin) or stays the same (like gold), exchange money for other goods/services. 
2) produce for money, pay bills and consume in same time period, shove surplus into gold/bitcoin/stocks, exchange gold/bitcoin/stocks for other goods/services in the future. 

I can see pros and cons of both those scenarios, but it's not obvious that, like @CliffBadger claims, either of them "fail" as money. They're both facilitating trade, doing money's role.  

denlillaapan

They aren't fully separable, but no one is claiming they are.

Ultimately, a currency that fails to be a SoV will fail to function as a medium of exchange, because of the point you make: we accept something as MoE because it's value stores long enough to exchange it for something else of similar value.

As you say, it only functions within a limited span of time, but money tends to be spent if it isn't worth saving.

econ

MONEY CLASS OF THE DAY: Money Illusion and Unit Bias, Bitcoiner style

They aren't fully separable, but no one is claiming they are.

Ultimately, a currency that fails to be a SoV will fail to function as a medium of exchange, because of the point you make: we accept something as MoE because it's value stores long enough to exchange it for something else of similar value.

As you say, it only functions within a limited span of time, but money tends to be spent if it isn't worth saving.