I never got involved in this discussion but anything over 8 gpm can be hard to feed since most spigots don’t put out enough. An 8 gpm is the sweet spot. Plus, you get up to 10 gpm and above you need 1/2" hose. You already know all of this though. It has just been kind of boring around here and you’re wanting some good conversation.
I know I said I never got involved in this discussion but you do realize you saying a 5.5 gpm can wash as fast as an 8 gpm is like someone saying a 3 gpm can wash as fast as your 5.5 gpm?