You don't need heat for dew control!
With this method, not only are you not introducing heat into your thermally stable scope, you also use less power:
Refractor dew control WITHOUT heat - it is possible
Where I live evenings can be veey dewy. I've been using this method for several months now with my Mak and refractors, and no dew issues while dew was dripping off the tube.
Heat does have a place, but it should not be on our scopes. We fuss to get our scopes to thermal equilibrium, and then we go and stick heating elements on the scope. Professional observatories do not use heat to control dew.
Alex.