To give a bit more detail, SPS and LPS are hobby terms rather than scientific designations. SPS generally have a large number of very small polyps that closely hug the skeleton whereas LPS have large polyps that frequently extend a significant distance from the skeleton. Things like torch corals and brains are considered LPS whereas Acroporas are considered SPS.
A Herbie overflow is designed to be very quiet but, IMO, requires someone to be pretty adept with plumbing for the initial setup. There are several DIY threads about building a herbie.