I realize this question was raised over a year ago, but in case anyone else wonders, here’s my take on it.
Test conditions were:
Water filled to the max level line
Lid off during the test
Starting temp set to 140°F
Starting water temperature 75°F
Breaking the question down a bit, the Sous Vide Supreme is capable of raising temperature at a rate of about 1.3°F per minute, or 52 degrees in 40 minutes. As far as controlling temperatures goes, the sequence of button presses necessary for a temperature change is <Set Temperature>, <Adjust Temperature (one press per degree)>, <Start>. So, the machine is capable if you want to manually control it. Setting temperature isn’t a matter of just 1 button press. Also, the buttons are membrane switches, and not really easy to actuate. Temperature control is stable and accurate though.
One thing to keep in mind is that the liquid containment vessel is not removable from the device. You can’t just pull a pan out of the machine and throw it in the sink.
I don’t think it would be a good idea to try to melt wax in the SVS.