My comments for what they're worth
(under the KISS umbrella):
I like PM miners or a diversified PM fund such as VGPMX for a few reasons: First, the miners have some leverage over gold itself. I have heard that it is 2-3 times the price of gold, so that if gold goes up 20% then the mining stocks should go up 40-60%. It's just the volitility in between that is the killer--and the timing. I think a smaller position in PM shares, especially if one is leary of commodities in general could be a safety bet if things go haywire with inflation in the future. I think 2-3% of the total portfolio is a reasonable allocation for an apocalyptic hyper-inflation event alone. The Hussman article posted on Raddr's site does a good job of explaining how gold functions in a rising interest rate environment--well worth the look.
As mentioned before, a significant drop in the US$ could also be an upcoming event in the near to middling future, due to our increasing dependence on external financing for spending/consuming. Most economic critics agree that at some point, other countries just won't want our $$ anymore, or if they do it will have to be at a higher interest rate. If the dollar devalues, I suspect inflation will rocket up, interest rates will jump, and, of course, your portfolio will appear appear to be the same size but actually buy far fewer goodies--and necessities.
If any of the above is even a slight possibility, would you want all your assets in US financial (read "paper") instruments or in something more tangible--such as commodities.
Although I've never been in the military, I believe that strategic planning there and in other fields says you should "Plan for the worst, but hope for the best." I think this is very important for your portfolio allocation too. Portfolio focus shouldn't be limited to "highest total safe return" and a mix of assets based solely on that strategy. This can skew your results if something unexpected happens.
--Greg