Eagle, I respect your Jeep knowledge very much, but I'm going to have to call BS on this one.
The transmission has no electrical input to determine how much the torque convertor slips, and therefore changing the electronics in the TCM combined with the power/comfort switch can not do this directly.
Indirectly, the convertor does slip more because in comfort mode all the shift points occur before the stall speed of the torque convertor.
Heat does not damage the convertor unless it is excessive heat. We know it's bad to run the 4.0 at 250 degrees, but you could use that same argument to say we should all install huge radiators and 160* thermostats to try and make the 4.0 run at 160*, which would not be beneficial. With reasonable driving, or with agressive driving and a good tranny cooler, the comfort switch will not indirectly create enough heat to damage the transmission or torque convertor.
It has been my experience as well that I get a few more city MPG when using the comfort mode.