There is certainly a lot of fact, myth, opinion, and hype on this topic. I think there is a point where the price vs. quality may not be what I would call justified, but it depends on how much you are willing to spend vs. how much difference you can expect to/will actually hear. (And 'different' doesn't always make something 'good,' 'better,' or 'best,' just... 'different.')
For instrument and effects patching, I prefer to split the difference and build my own cables. You can buy Canare and Mogami cable and Neutrik and Switchcraft plugs from suppliers, make your own leads to the exact lengths you desire, and save quite a bit of money vs. buying ready made cables with those same components. One of the big factors in higher-end cables is the capacitance rating. The lower the number, usually the 'better' it is, ad it tends to roll off less high end the longer the cable is. A well-made cable with low capacitance and good construction/materials will typically sound better longer due to better durability than a truly 'cheap' cable. If you are happy with the sound you are getting with the PW's, I wouldn't worry about replacing anything. There are plenty of people who are perfectly happy with that brand. I've been using the Mogami wire with Neutrik plugs, from Redco. I can make a 15' cable for about 50-60% less than a pre-made costs. I might try Canare and Gotham next, just to see how they compare.
The Mogami sounds fine, so I'm not feeling like I may be missing out on something. I think that is a part of the mythos, that a lot of us fall in to, that there will be that one cord, one pedal, one pick, one pickup that is going to turn our contentment (or hatred, lol) with our tone in to sheer auditory bliss. IMO, it's just not realistic, beyond a certain point. I can't listen to my tone through my current rig and accept the idea that adding a $250 10' cord is going to make my eyes pop out of my head. But then again, I'm happy with an amp that cost me $650 used, from a brand that many on the internet despise. So take that as you will.
With speaker cables, I haven't really experimented too much with the various 'exotics.' As long as the wire is of good quality and the gauge is adequate for the distance and amount of power I am pushing, that is all I really look for. It's not as critical (IMO) as the properties around a line or passive signal in a guitar cable. Right now I am using a Horizon (I believe...) speaker cable, probably rated for far more than the 50 and 100 watt amps I use with it.