My experience pretty much mirrors @whart I well remember hearing the big Maggies with all ARC setups, one of my early references for high end sound, this in 1970's. I only owned a single ARC piece, this SP9MkIII, very disappointing, one of their 'bleached' out offerings.
I too migrated towards horns and SET amps, this gradual move over a number of decades and experience with a variety of amp topologies. I don't doubt you'd find some more recent ARC offerings to match well with the Maggies, my issue is the more powerful the tube amp the greater chance for reliability issues and expensive repairs due to added complexity. High power tube amps put out a lot of heat, heat is the enemy of reliability.