Mike,
Most of the best new ideas and innovations in audio are discussed, beta tested and shared on forums like this one, not in the mainstream mags. I doubt the professional rags would waste their time, space or reputations reviewing an ugly, $79 utility tool sold to machine shops. It's much more impressive to review an $1800 Furutech DeMag, which does exactly the same thing with the addition of an auto-timing circuit, a shiny case and a selling price that brings the buyer some cache and the magazine some ad revenue.
Personally, I'm happy toggling the on/off switch and controlling the strength of the magnetic field manually, exactly as one does with the Walker Talisman. I can buy alot of records with that $1721 in savings, not to mention the amount I save by not subscribing to the usual mags. ;-)
You'll note the mags haven't reviewed the Magic Eraser either, and probably never will. Why review a stylus cleaner we all buy for pennies at the supermarket or Walmart. It does a notably better job than the $25-50 stylus cleaners sold by advertisers, so an honest appraisal would risk ad revenue.
BTW, I hope no one uses *any* demagnifier near their TT, preamp or any other component. Demagging should be done well away from your equipment. Anything else would be foolish.
FWIW, we demag each LP before it goes on the RCM. There's some chance demagging before wet cleaning might help loosen certain grunge and the strength of an AC powered demagnifier means the effects seem to be fairly permanent (as with the Furutech) so it doesn't really matter when or where you do it.
Doug