I read Yvain's report and compared it's reasoning on potassium to the DRI DIETARY REFERENCE INTAKES FOR Water, Potassium, Sodium, Chloride, and Sulfate from Standing Committee on the Scientific Evaluation of Dietary Reference Intakes of the Food and Nutrition Board (http://www.nal.usda.gov/fnic/DRI/DRI_Water/water_full_report.pdf). My understanding of potential concerns would be:
Serum potassium (responsible for the sodium-potassium pump etc.) is only very weakly linked to potassium intake, as the kidneys are very good at both excreting extra potassium and keeping potassium in the body if intake is low (though the kidneys are not as good at the latter as the former).
Potassium's effect on lowering blood pressure is through the sodium-potassium balance, so potassium helps you mostly if your intake of sodium is too high.
Increased potassium intake's potential beneficial effects are supposed come from a better acid/base balance in the body; but there is little experimental evidence (as opposed to epidemiological evidence)
I don't think the epidemiological studies give reliable evidence for potassium, as the main source of dietary potassium are fresh vegetables, which already correlate with lower mortality on their own, as well as correlating with many lifestyle differences.
In animal studies the 'good' potassium was potassium bicarbonate, not potassium chloride, but most supplements have potassium chloride.
From other sources/common knowledge:
My conclusion: it might indeed be beneficial to increase my potassium intake, but I would have to do it by increasing consumption of vegetables high in potassium rather than by taking supplements.
If you enjoyed Paul Fussell I highly recommed Bourdieu's "Distinction".
It addresses many of the criticisms about class and taste claims expressed in the comments: It is extremely data-driven instead of relying on 'common knowledge'. It describes not only how different classes' tastes differ but how those difference evolve over time, and not only a single hierarchy of classes but the different fields in which classes operate.
Bourdieu doesn't seem to be part of the lesswrong canon, but could well be. He has an undeserved reputation as (only) a theorist, whereas to me his strength is in his use of large bodies of data (but not experiments, alas). The books can be heavy going and to remind of diseased discplines, but the data is great.
If anybody wants to get deeper into how fashion, class and status work I highly recommend Bourdieu's 'Distinction: A Social Critique of the Judgment of Taste'.
Bourdieu collected large amounts of data on the expressed taste of different social classes in visual art, food, music, literature, social gatherings etc., augmented by semi-structured interviews with a smaller sample. It's not too useful to try and summarize it, but some of the major useful concepts include: Fields (not everybody plays the same status game), Distinction (actions and taste are arbitrary, but need to be distinguishing) and Objectification of taste (how society and the educational system measure taste and conflate it with skill).
Bourdieu is somewhat unfairly known for his theory, but I find he's data-driven sociology extremely compelling (he used just the kind of surveys my sociology teachers kept warning me about in the early 90s).