Hi All,
Thanks for the replies. Here are my comments/questions on some of the points raised so far:
* The rate of the CD I'm investigating is a little over 7%. It's not in USD, but it's in my "home" currency (AUD), so (I think) that means I'm not taking any abnormal currency risk.
* I apologize for using the word "zero" (and in all caps no less

) I agree that CDs have a non-zero risk of capital loss. What I was trying to say is that if you invest, say, $10k in gold, $10k in shares, and $10k in a CD, then on some random future date you probably wouldn't be surpised if you had less than $10k in gold or shares, but you probably would be if you had less than $10k in the CD!
* To investigate the comment that the PP "yields roughly 9% per year" I did some (very rough) mucking around with the numbers in craigr's historical returns page:
- When I took the simple average (no compounding) of the PP's annual return from year X until 2009, I found that it's only above 9% for X in the 1970s. If X is any of the 30 years from 1980 onwards, then it's below 9% (because the spectacular PP year of 1979 is excluded). Furthermore, starting in 18 of those 30 years, the average return to date is less than 8%.
- Simba's spreadsheet also has a tab where you can do this sort of thing for every year from 1985 onwards. There, the PP does better than an average of 8% only if you start in 2002, 2003, or 2005. It's lower than 8% starting in every other year, and lower than 7% starting in 8 of them, including the entire half-decade 1996-2000.
- So I guess my conclusion is that a guaranteed 5% vs a rock-solid 9% is not very interesting, but a guaranteed 7% vs a less-solid 6-8% is moreso (at least to me

)
* I have some questions about the comments that "the PP has inflation protection built in" and that "the PP does a good job of providing consistent real (after-inflation) returns". I'm pretty clueless about inflation, so the following are genuinely ignorant questions rather than anything else they might appear to be: Why is it that we can make "inflation-resistant" claims like this? Is it solely because of the 25% gold component? If so, does that mean that a portfolio with, say, 10% gold could make a like claim? Similarly, does that mean that portfolios without gold can't claim to be inflation-resistant or to deliver returns that are inflation + X%?
* Finally, I just wanted to reiterate that the idea is not that the CD will definitely (or even probably) beat the PP over the next 5 years. I'm just speaking as someone who has been attracted to the PP philosophy because it offers the combination of a sufficiently low chance of capital reduction combined with a sufficiently high (but unspectacular) historic rate of return. And I'm exploring the idea that once CD rates get to a certain level (and 7% may well not be high enough) then they too seem to offer this combination. Or does the spectre of inflation mean that this will never be the case?
Thanks again!