I am guessing that the sonic improvements from the cap upgrades are pretty subtle, just likely to be a tiny little bit of extra smoothness in the highs. Might not even be audible. Even a properly setup pickup in a $$$$ topnotch arm on a multi-$1000 table has over 1% intermodulation distortion through the highs, mechanical transduction of a wavy vinyl groove is not a low distortion process. My guess is this nonlinear distortion would mask any subtle improvements brought about by capacitor upgrades and the like. But, the more linear the electronics are that follow the pickup transducer the less likely they are to EMPHASIZE the nonlinearity inherent in the mechanical process. So maybe... who knows. The caps were part of the Cornet I bought, so I kept 'em.
One thing that MIGHT be audible is the RIAA equalization. The Teflon caps used in the RIAA eq have a closer tolerance than the original caps, so channel-to-channel frequency response differences might be tighter, and this might be audible.
From my experience the sonic differences that arise from using the NOS Raytheon 6SN7 instead of the 12AU7 as the cathode follower, and from using RCA 7025's in the gain stages can be fairly audible, because it changes the harmonic "flavor" of the inevitable distortion added by the active stages.
Using all that copper, I doubt it makes ANY difference over an aluminum chassis. Maybe if you were in a high RFI environment, like at a radio station in it's strong RF broadcast field, it might reduce RFI a dB or something. MAYBE. It sure looks nice, though- and the original builder put it in there so I retained it, and polished it up.