works just fine on my 8w heat pad on my 10gal with the baby bearded, for a dimming a single device cant beat it.
if your doing 2 devices you can make your own dimmer with a single pole wall dimmer, a wall socket some wiring, a grounded extension chord repair kit, a double wall box and some brains. i made one although im just running the UTH on it right now if i add another pad to help the hot side i can regulate them both in unison.
i should do a parts list and a how to some time.