I followed the other thread when it was started and have been waiting for this one. I'm with you JD as far as exercising caution here people.
I have no issue with this method, I have actually used a modified shorter version to hasten samples along. Additionally, the "modernist cuisine" or "molecular gastronomy" trend in the culinary world incorporates microwaves for a few purposes and there are some sound principles going on in your technique. It is questionable that the sugars are caramelizing using a microwave, the product just isn't getting to the proper temperature for long enough to cause the sugars to caramelize.
Ultimately it sounds to me like another progressive steeping method that may prove valuable to some, and will have a multitude of naysayers . I'm a throw it in the steep box person that uses some hot water baths to help mix. No ultrasonic or crock pot (I just don't have them or I'd try them...) and I just don't have time...
HOWEVER (ya'll knew that was coming)...However, Visus (and I'm NOT bashing you at all or the method) I personally feel from using microwaves professionally that you should provide a huge, HUGE, bigger disclaimer and warning than you already have in your original post about the potential danger. My biggest concern is absolute newbs may throw their juice into a microwave and shake or move the bottle while removing it and have scalding hot pg/vg erupt while looking into the bottle. People don't always read posts or threads all the way through etc... etc...I'll get off my soapbox. Just my to cents, I'm supportive and hope I didn't offend. Just trying to avoid liability.