Both of your examples are extreme mismatch. Playing a $2000 cart on a $200 table will not be acceptable. A $2000 cart will most likely be a mc or a high-end mm, they will require a precision arm and careful setup to sound good. A $200 table just doesnt have the precision they need. It is a waste of cart and money.
Playing a $200 cart on a $2000 table is a more acceptable mismatch although I wouldn't do that either. If I had $2200 to spend, I would have bought a $1500 table and arm with a $700 cart.
In your case, the Shure actually is a very good cart (I have one) and it certainly desires a better table and arm to show its stuff. But for $450, I doubt you can buy anything significantly better than the Thorens you already have. If I were you, I wouldnt do anything right now but save more money toward a better table and arm, probably a used set in the range of $700 to $900.
Playing a $200 cart on a $2000 table is a more acceptable mismatch although I wouldn't do that either. If I had $2200 to spend, I would have bought a $1500 table and arm with a $700 cart.
In your case, the Shure actually is a very good cart (I have one) and it certainly desires a better table and arm to show its stuff. But for $450, I doubt you can buy anything significantly better than the Thorens you already have. If I were you, I wouldnt do anything right now but save more money toward a better table and arm, probably a used set in the range of $700 to $900.