Snails' feces contain relatively few nitrogen, and other nutrients in high demand (phosphorus, micros). Therefore their attractiveness to microbes depends on general balance of nutrients in the tank.90+% of all the mulm in my tanks is probably from ramshorn snails that produce far larger poo than any of my fish.
A massive benefit for me, both as detrivores and as a mechanism for encouraging and maintaining microbial diversity <"https://www.pnas.org/doi/10.1073/pnas.1218525110">*.........Do they actually add anything to an aquarium?
In reef keeping, certain species are crucial to the tanks “up keep”. But when I’ve kept snails in a planted aquarium, I’ve never truly felt any benefit to having them