Jeeps ! As if cart/arm mechanics wasn't hard enough to work out, we need another spring/mass/damper system in there ?
Once one allows the cartridge to vibrate in the headshell, one can pretty much give up trying to analyse or predict what might be going on. Especially when the materials are non ideal, in tension, and held by rigid bolts which allow compression but not extention. Good luck, the outcome can really only be assessed imperically !
One global prediction: all effects arising are likely to be at LF, and affect stability. That's not to say there aren't knock on effects in the audioband, but LF response and stability are most likely to be affected in my book.
One has to ask 'what problem are we trying to solve' with such mods. It's a long shot, but it just might work trying to match underdamped cart/arm situations, or where res f is too low for stability. But pretty obviously, it's generally ad-hoc as to outcome.
Just about all the descriptions of 'energy flowing into the arm' are enough to invoke apoplexy really, it's nonsense. Such things are always diabolically described, even if imperically they have an effect.
Decoupling the cart from the arm is a true act of last resort, in my book. But hey, it's still legal