I ve been using a Scala 2 on my Hatteras for 2 or 3 years now and it s been pretty good. Doesn’t put out as much pressure as the Mach 5 but it s fine on my boat with electric heads. Doesnt work with HH heads which need more pressure
Still have a Headhunter for salt water wash but replaced the freshwater one with a much less costly 230 v. Everbuilt Shallow Well Pump HD sells. Works great. for galley, two bathrooms with two fresh water heads.