In regards to the "tone ring" discussion... I never knew what a Fender Tone Ring design was but the explanation cleared that up. When I first saw Guilds version of the "tone ring" the design implied to me that 1) the design utilized the out-of-phase backwave to cancel out the low frequency response of the cabinet and speaker. That would be the main design rationale. 2)The next feature to impact the tone would be the volume of air in the back cavity which based on volume may spike up the tone somewhere in the 200 Hz to 1000 Hz region and 3) the resonant frequency of the "air port" surrounding the speaker. Its a pretty big port so likely resonant too low in frequency to influence the lower frequency cab tone.4) the fact that the speaker is recessed 1 inch isn't a dominant tone changer but just like a guitar all the subtle wooden shapes have subtle tone qualities.
Being an engineer who worked with fields and waves, some acoustic background and a lifetime of messing with music, speakers and cabinets I figured I would add some comments. Not trying to sound like know-it-all cause when it comes to these things there are always exceptions to the rule.
M