I'm really simply curious. All of my phalaenopsis orchids are on warming Matt's. I turn these way down through spring summer and early fall and turn them up a bit through winter. Which Sparks the question to myself, what would be the result of too much heat at the roots other than drying out too quickly? Or would that be the only result?
That is an interesting question. I know that, with most plants, keeping the soil warm is very good for growing roots. With cuttings of some plants that are difficult to root, heat is usually the key to success. I would think that a heat mat, then, would improve root growth. As I do not have much experience myself with heating mats, it will be interesting to see what others have to say.
As long as the temperature at the roots is under 90-92 degrees during the day and drops somewhat at night your plants are going to be fine. Much higher and they're going to be baked ziti.