I've always suggested that everyone have both (provided that they already have taken the responsibility to have one and they are not an average idiot when it comes to monetary science.)  Someone who did well in BTC should, in my opinion, trade some of it for silver at least (junk coins) and if they have a large budget gold as well.  Conversely, as I've always suggested, people who protected their wealth by putting it into PM's before BTC came along should really consider converting some of it into BTC or one of the other more well maintained crypto-currencies.

BTC and PM's are, to me, nearly identical asset classes.  Both are in the category where one can autonomously control them without the participation of other entities, and are not 'someone elses liability' (meaning you don't have to rely on someone else to make good on a piece of paper and rely on a functional court system to enforce your property rights.)  At the same time, BTC and PM's have vastly different capabilities in terms of transportation in particular.  Also in the anticipated usability during a crisis.

We're getting a ways off the topic of this thread though.  But you asked.