Heat matts can reach 80C+, heat lamps (ceramics) 250C+. I wouldn't use either without a thermostat. No idea what heating will do to juice but I keep reptiles and have seen what a unstated matt can do to wooden vivs.
What does the heat do for the juices? I am sure Grant told me to leave his juice in cool dark cupboard. Does it vary between different recipes?
Not 100% sure myself, just read this from AC and thought about heat
This is a recommendation for all shop purchased e-liquids not just ours, all will improve with some steeping, manufactures usually bottle as soon as a juice is made, this halts the steeping process to a degree, employing the "cap off and dark warm place method", will improve 99.9% of juices.
Top tip from Moggy ... leave on a computer or on a laptop ... computer chassis will give a bit of vibration, plugged in laptop should have just about right amount of heat. I normally use a radiator but heating is off currently