Here is what I have found so far regarding HFC cables.
First, the biggest change I have heard so far is merely adding one CT-1 cable into my system.
Second, there doesn't seem to be a "bottleneck" when adding more HFC cables, i.e. the more magnets the better, no matter whether you add CT-1x to replace another brand of cable, or whether you upgrade one or more of the HFC cables. I have had other cable brands where adding one cable didn't make much difference since another cable elsewhere in the system was the limiting factor. Conversely, with HFC cables you could have all regular CT-1s and adding a UR cable would make a big difference.
Third, the further up the line, the greater incremental change, i.e. UR change over U is greater than U over E. And it ought to be given the ever-increasing price difference as you go up the line. Going from U to UR is simply amazing.
Fourth, the closer to the source, the greater the effect. I have found the biggest changes to be from my turntable with 0.5 mV output cartridge to my phono stage, the next biggest from my phono stage to my line stage preamp, and so on. For signal cables, the least effect (still a big change) is in speaker cables. This makes sense since intuitively it would take a bigger magnet to affect a greater voltage signal.
Signal cables seem to be more affected than power cables, but all still have a big effect.
Waiting to hear how much difference the magnetic adapters make.