Success tempering chocolate with Kitchen-Aid heated mixing bowl?
I haven't used the Kitchen-Aid, but I have the Kenwood Cooking Chef which is similar, and I frequently use it to temper chocolate. I have tried a couple of different ways:

Heat the chocolate to 32°C degrees while stirring - This takes a long (looong) time and the results are not great (too viscous)
Heat the chocolate to ~40°C while stirring, then lower the temperature to 32°C and add about 10% finely chopped chocolate, stirring until it's all melted. - This is faster and fairly foolproof, but the chopped chocolate takes a while to melt.
Heat the chocolate to ~40°C while stirring, then lower the temperature to 32°C and add about 1% mycryo (fine cocoa butter crystals) - This is faster and the best I've come up with yet. Note - You must let the temperature of the chocolate come down to about 36°C before adding the mycryo - or it will melt them completely, ruining their special crystalline structure.

Another thing I have discovered is that adding ~5-10% cocoa butter makes for a less viscous chocolate that's easier to work with, especially if it's to be poured into moulds. (It's easiest to add it at the beginning.)
I use a rubberized spatula that scrapes the bowl. I assume Kitchen-Aid has something similar.
Adding cocoa butter is controversial. Some people claim that it's cheating, but I find that it gives a better shine and snap to the finished product, without affecting flavour noticeably.