The Envirolet Low Water Composting Toilets may seem like a great idea for water saving as they flush with only a cup of water then compost the waste using microbes but I hardly see these hitting the main stream being used in very many houses. The system seems well thought out in terms of venting to avoid odor issues but it sure seems to bear a strong resemblance to toilets used in campers and as heads on boats. While the toilet may be a fine convenience in those applications it is hardly something I see people as wanting in their home. Add in the periodic servicing AKA taking out the compost and how many people would possibly be interested. I my opinion I think many people would share that opinion.
The waterless units make some sense as they can be used year round in cabins that are not heated without worry as they can provide a worry free toilet for those at camps in the wild without a source of heat or, running water. In those applications it may be an attractive unit that is better than the alternative of porta-potties and old timers where you have smells and need to dig a new pit every few years or have to pay for servicing.