We've seen a 125% gain thus far this year...so the price could stay this way for 5 years and we'd still be able to claim 25% growth year over year. That's more than we've seen with gold historically.
The only thing I'd see attractive in gold is that it has never gone out of style. People has always valued it. I see gold more as a store of value rather than a instrument for growth. Not as convenient as bitcoin but if you have enough money to invest in multiple stuff, it probably wouldn't hurt to have a bit of AU.
i don't agree with your defaltionary definition about, bitcoin, it's not the price of the good that falls, it's bitcoin that increase and have more power in purchase
for fiat can be seen in both case, inflationary because they lose value due to infinite printing, which make their coin have less and less value over time, or because the goods increase in price
And the ever increasing value is not much of a problem for bitcoin because of the satoshi system. You don't see fiat with 8 trailing decimals units.