I looked at this a while back. Spoke to ASS about this and they never mentioned the need for mechanical mixing. They made it sound really simple, but I did wonder about proper mixing of the sand and 'magic sand' together. The magic sand is liquid, isn't it?
Glad I gave it a miss now.
Let us know how you get on though, especially regarding the results when you get to grips with it.
Incidentally, did you only buy one for testing or more for specific jobs?
Good luck!