Just a note to consider...
The Hum Debugger and shielding work on completely different principles.
Shielding attempts to block environmentally-induced hum from sensitive components in the guitar. It has limited value to true single coils, as part of the pickup is still exposed to environmentally-induced noise. I've completely copper-shielded my Strat and still get some hum. Like, I said, this is to be expected. I pretty much knew that the fact that the surfaces of three pickups were still exposed to the environment would mean that I was, at most, shielding the controls and internal wiring. But, I was curious as to how much of a difference this would make.
The Hum Debugger, on the other hand, essentially attempts to notch out the offending frequencies from your guitar signal, which will be the fundamental and the harmonics of power line frequency.
Pickups, on their own, have nearly imperceptible inherent noise. For all intents and purposes, you could say they have no inherent noise. The only reason they make any offending noise is because of what is induced into them externally through the air. This is the very reason humbucking pickups even work...
Ok ALL who posted here including GW, Robert, Smitty, DONO AND BDON and Adrian.
As Robert clearly expresses his dislike for Single coils, the first inclination is to think his dislike is based on the hum that comes along with Singles and if he would only be able to copper shield or completely filter out all noise from singles that he would be fine playing a SS, or SSS guitar. However, as I have conversed with him through the years, it is not so much that his dislike of the hum but the actual sound singles reproduce. If given the choice of making music with them or Humbuckers, he would rather hear Ratt, Leslie West, Collen, Iommi, etc. over the likes of today's Clapton, SRV, KWShepperd, Frusciante, etc.
As for the efficacy, of the box GW posted this about, I won't address that device or the copper shielding or faraday cage aspect of this thread. In summary, Smitty sure knows his hows and whys of electronic noises, pickup design and how to match the options out there to achieve various tones. As for Robert, he is not interested in various tones, but achieving the perfect, tones he hears in his head from his hands and the hands of his favorite players. Once he finds the combination of Guitar, Pots, Caps, Strings, Pickups etc, then the tone must be without flaw such as hum, wolftones, twang, warble, buzz, or even lack of the desired amount of gain like he was seeking to massage or beat out of his DSL 40C. Only then will Robert have "IT."
Having said that, "IT" will never be the sound of a single coil even if it has noiseless shielding, noiseless pups such as in his Squierstrat, noiseless sound gate, or hum debugger.