How many dozens upon dozens of road cases does Metallica take out on tour for staging, PA, drums (+ even more of those stupid giant floor toms on this tour), and even for wardrobe/back stage stuff ? What are they really saving by leaving the tube amps at home ? Those fractals are housed in sizable road cases as well. How much lighter/smaller is that compared to tube amps in a road case ? Most international touring bands using tube amps have duplicate rigs in North America and Europe to cut down on shipping already.
As far as consistency they had already worked out a system for consistent live tone since the black album tour using mic'd isolation cabinets. Oh gee, I guess that was another 2 road cases to schlep around. I'd rather have an inconsistent tone that hypothetically might vary from a 6/10 to 10/10 night after night than be straddled with a half assed 5/10 (I'm being generous) bland tone like Metallica "enjoys" nowadays.
Sadly Metallica's tone has gone the way of Lars' drumming. Lazy, uninspired and a shadow of what it once was.