dunno about which uses more electricity. probably a lamp cos its a higher wattage.
as for using a dimmer stat with a mat. habistat dimming stat require a minimum of 40w and the microclimate B1 dimming stat require a minimum of 5w. i do think some people use habistat ones with mats though...
i'd go for a heatmat over a lamp any day for a corn. an 11" x 11" mat is likely to be around 15w and the lowest wattage ceramic bulb i've seen is 40w so the bulbs can use a lot more electricity. also corns don't need 'basking' heat - another reason to go for a heatmat.
cornsnakes, ratsnakes, bullsnakes, boas and day geckos