I used to run 130's and 120's (or their variants in the Sunn cabs and Fender Twins at the time) and at one point got to try a cab with what I believe were three fifteen inch Altecs.
Assuming that was the 418 (were there others in the line?), my memory was of it being a lot looser or a softer/easier breakup, and an odd impression though that remains- their sounding like paper.
Or, from the other angle, JBL's cleaner, more dynamic.
Understand this from a hell of a long time ago too. Playing style- 335, and quite a bit on the cleaner side of things.
Long time part-time