I would imagine that letting the soil "cook" (compost) is a big part of their success, it wouldnt be hard to deal with, just keep a couple bins like they said, and that should give it time to cook between uses.
Also I was thinking it may also be benefitial to pasturise the soil before using it, this would kill many unwanted organisms, and let many benefitial organisms live.
(For those who dont know how to pasturise: Place soil in a plastic zip lock bag, place bag in a pot of hot water kept between 160-170, leave it there for an hour or so, pull it out, let it cool, and it's done. DO NOT LET THE TEMP OF THE WATER REACH ABOVE 175F, but leaving it in longer than an hour is cool.)