IMO, as far as sumbersible pumps go, they are one of the better ones out there. There are other players.. Quiet One, etc ...I use mags for all of my submersible applications, and I've never had any problem with them.
In fact, my freshwater planted system has a mag 12 return pump and a mag 9.5 feeding a Co2 Reactor that have been running non-stop for 3 years now with no problems whatsoever.