This is very interesting and I thank you for posting this, marmalady. I've tried the microwave method, but failed miserably at being able to control the temps that way. It has been my experience that chocolate, despite its versatility, is exceptionally tempermental (pardon the pun) when it comes to tempering and has a precious, small range of temps in which it works best.... Would that I could have achieved this in the microwave!
I have spent untold hours practicing Torres' method of "Tabliering" on my slab, determined to perfect the age-old method, and while I did to substantial degree, I also discovered that manipulating the crystalization via heating and cooling of water changes in a double boiler worked just as well, and was a much cleaner, simpler method of achieving the same final high gloss, hardness and bloom resistance.
Torres is a chocolate genius, in my opinion. Absolute proof of that, for me, is that he can temper using a microwave!!! And I've no doubt that he does so spectacularly and consistently well!!
Pain is inevitable. Suffering is Optional.