I just use regular wax. Once every 6 months or so I pour a few cups of water into the crock pot, heat up the wax and let it cool. Most of the gunk in the wax settles down into the water and the cool wax 'puck' on top of the water is clean.
I would only use the Molten Speedwax if I was doing a TT where the extra 1/2W might be worth something. For everything else plain wax seems adequate and is a little cleaner.