raider,
there is some synergism, but the heat that you feel is due to the action of capsicum- which has some thermogenic properties (not as much as the heat would lead you to believe) as well as some local diuretic action.
It definitely is a good carrier, which is why i have reccomended it, but not the best. combination carriers/penetration enhancers are better. though future versions of the carrier solution mentioned may carry capsicum, though at less than .025- because many people are too sensitive to capsicum to use that dosage.