Well, if you take a look on my recent post you'll see we are in the same boat.
For what I've researched, it comes to this:
+ They don't eat plants - ever.
+ They don't lay eggs
+ They eat decaying matter, refresh and aerate the substrate
+ They eat diatoms (brown algae)
+ They look very cool and neat
+ Many plant breeders and old-school aquarists recommended them in a heartbeat.
- They breed like crazy
- Point of no return: once there they will always be in your tank, whatever the numbers.
- Periodic removal of their numbers is required, either manually, netting them on the glass, using baits or as a last resort, using assassin snails or fish that eat snails.
However, this snail will never harm your tank. People write crazy stuff about snails, some even use nasty chemicals to get rid of the snails. I could never understand that. Snails are part of the nature. MTS even in large numbers won't do any harm, except making your tank look ugly. Or freaking you out with their crazy numbers.
That being said, I'm still on the fence. Mostly because I suffered from a very mild case of molluscophobia. I love and even admire snails now, although I still cannot touch their bodies with my bare hands. But looking at hundreds of them at the same place still produces some terrifying feeling in my stomach. I hope to overcome it by finally introducing MTS to my tank.