I would never pass myself off as anything approaching an expert at carburetors or how to tune them, but this seems to be using a secondary input (the heat of the header primary tubes). They can be affected by other things than just the mixture or balance. That's not to say that it won't work.
It reminds me of a story I read many years ago when Mark Donahue was starting his professional racing career. He wanted to adjust the front/rear brake balance on his car for an endurance race so he drove it at night and had someone watch the glow of the brake discs. When the front brakes glowed brighter and earlier, he figured it was right. However his teammate was an established driver and quickly found that he had screwed the balance up horribly!
Obviously, this isn't directly analogous since he was only able to go by the color of the rotor not the temperature but it seems like a reasonable way to go about if you don't know any better.
For mixture, I would trust reading the spark plugs and for balance, I would use a uni-syn or similar tool (I've seen people balance carbs successfully using a piece of hose and listening to the whistle).
