MTS = Malaysian Trumpet Snails
CRS = Crystal Red Shrimp
There is an advantage, like with MTS, over other snails. MTS for example dig through the substrate and prevent the "death bubble". I keep them in all my tanks.
As for the poll, if they don't do any damage to my plants then I'm fine with pond snails. They are in every tank. Once a month I do a small removal with zucchini and fishing line.