I believe the capacitor in the "Quieting The Beast" article has nothing to do with hum reduction. It is there to prevent electrical shock in case of a severe electrical malfunction in your amp or at the location in which you are playing.
As for the uf, actually the 'u' is the Greek lower-case letter 'mu' or µ (do you see that slight curl in the lower left of that letter? If not, go here and see the entire Greek Alphabet: www.1728.com/greek.htm
The µ is an abbreviation for millionth and the 'f' means farad, which is a HUGE unit of electrical capacitance. That's why you'll usually run across capacitors in the microfarad, nanofarad (billionth of farad) and picofarad (trillionth of a farad) ranges. Instead of µf sometimes people will use mf or mfd but maybe it doesn't look as impressive. Also, it is only recently that nanofarad and picofarad have come into common usage. Previously, capacitors were listed in microfarads or micro microfarards (1 picofarad). So, for example, a 200,000 mmf capacitor equals a .2 mfd capacitor. More information than you probably evr wanted to know huh?
Shibby I know this might sound like GuitarNuts heresy, but I have never installed the "shockproofing" capacitor in any of my guitars. However, I don't play anywhere except in my own home. By all means, read John Atchley's article about the possibilities of electrocution - they are quite real especially if you are playing in an unknown setting. The wiring could be so bad that the outlets might be wired backwards so that the hot and neutral wires are reversed. (Very dangerous).
I dont know if it will give you protection but I used a 250v 1uf cap in mine just recently. I never really gig out much but I do use tube amps. I hope it will give me a little protection but I dont think it would last long if a big enough current came down the wire. I just dont htink it happens that often. I may be wrong though. Good luck Peace Damian.