From all this discussion, and my experience, I'm beginning to think PetZyme or something like it is the appropriate substitute. Perhaps it is even more appropriate than the original Sanisolution, about which flyguyjake points out numerous concerns.
It seems to me that the whole point of a litterbox is not to have a sterilized environment, but a place that's reasonably clean and odor-free. Not only can 100% sterilization never be achieved, but there are dangers in even trying, as we see in this thread. If a cat poops in the wild, is that patch of soil 100% sterilized? No; that is what cats' immune systems have evolved for millions of years to deal with. Anyways, just hooking the Genie up to hot water probably does quite a bit of sterilization, and should be safe (more discussion of this in the "hot water" thread).
I use PetZyme, with the Genie connected to the hot water, and it seems to work great. The hot water dissolves the micro-poops, and keeps everything inside cleaner. The PetZyme breaks down the waste organically, and leaves clean scent that the cats don't seem to mind. In fact, it leaves things smelling significantly better to me than either the regular or scentless Sanisolution. According to the manufacturer's web site:
The bacteria used for producing Petzyme are Bacillus subtilis, Bacillus licheniformis, and lactic acid bacteria.
Bacillus subtilis, Bacillus licheniformis, and the lactic acid bacteria are GRAS (Generally Recognized As Safe) by
US FDA and the AAFCO (American Association of Feed Control Officials).
http://atp-tech.com/images/Petzymesupportinginfo.pdf
I had a passing concern that the beneficial bacteria and enzymes would not survive the hot water. But since it has been pointed out that cleaning fluid is dispensed during the drying cycle, I believe it has a good chance to work one way or another. Also, as others have pointed out, it does not leave a sticky residue. $12/gallon at Pet Smart.

