There are two models of the Precise Heat Mixing Bowl -- one for bowl lift mixers and one for tilt head mixers. I have the bowl lift model. William Sonoma is where I bought mine. WS has a good return policy as I recall.
Measuring the percent reduction by weight is something I cannot do with my current setup. Not that I wouldn't like to. However once you get the variables figured out, cooking in the PHMB is reproducible. The variables are temperature, time, and mixing speed. (Neglecting ambient temperature, relative humidity, and I suppose atmospheric pressure.)
Ruben's method fixes the temperature, so the variables are then time and mixing speed. Once the proper reduction is achieved the recipe result can be repeated over and over without thinking about it.
Here is what I'm doing: I heat the ingredients quickly on the stove (in a pot, not the PHMB) to 160 deg F (this takes about 10 minutes). I pour the mixture into the preheated PHMB set to 198 deg F, and mount the PHMB on the mixer, set at speed 4 with the wire whisk, and cook for one hour -- completely hands free and unattended. The mix stays at 160 deg F. This is all with the lid off, of course, if that was not clear.
After the cooking is completed I homogenize and chill the mix in an ice bath as normal.
Edit: it may be possible to skip the stovetop step and do all the cooking in the PHMB but I haven't tried this yet. I'm sure it will take longer to come to 160 deg F.
