Sounds great - too good to be true?
What are the drawbacks? I’m sure there must be critics - what do they say against it?
Nothing. It literally solves the problem. The biggest part is dealing with some of the utilities. Some don’t like change and getting them to hook you up to the pipeline can be a major pain in the arse.
The other is the they must be managed correctly. They’re not terribly tricky but you have to make sure no bacteriacides get in the manure.
Other than that they are very much a miracle technology.