One of the interresting and effective techniques used by Weller on its (I think) TC201 irons is a magnetically activated thermostat they call a magnetostat. The switch is activated by a magnet located just to the rear of the replaceable tip. The tip is purchased for a specific temperature and has a ferromagnetic slug that becomes non-magnetic (actually, paramagnetic) at the Curie temperature of the specific alloy of the slug. This allows the magnet to drop away and turn off the heater. So, it is sensing the temperature of the rear portion of the replaceable tip which is not perfect, but better than sensing the temperature of the heating element.
For years I got along fine with a poor man's homemade "temperature control" consisting of a fast-response, low-voltage iron (GE 6 volt, I believe) and a gravity-activated switch that switched to a lower voltage tap whenever the iron was hung on the hook. I don't recall having to wait noticeably for reheat upon picking up the iron. It's main virtue was saving the tip from oxidizing during idle periods or if I forgot to turn the iron off, but still having the iron almost ready for soldering. Could also use a thermostat or thermistor to sense when you hang up the iron.
awright