I generally havent had problems with squealing, but I have noticed that at times, when it is very humid out, it happens (not wet, just humid)

This does appear to occur more when I have first set up pads, and over time it goes away, I assume its because the pads wear down a certain amount and the pad surface changes. I kind of equate this to the pads "bedding" in to the rim, although I could be wrong on this-but it does seem that the problem goes away after a while when it has happened so isn't a problem really.

personally, on my canti bike, the salmon coloured pads have been fine for being quiet and effective stoppers. My first front pair lasted four seasons, pretty good for supposedly soft pads (I don't live in the mountains however and keep the bike clean, so this is a big factor)