MJ impellers don't care which way they spin, so I remember when people were first doing the mod, they had problems with the impeller turning in reverse, I would think that the commercial version has circum this delema, other than that as long as the pump can take it the mod can, and MJs are fine for on/off application. I heard they are a bit louder than a regular MJ
I too have not owned them, just read a lot about them.