Hi angel,
I'm a firm believer in a good buffer for the gainclone, and use an old fashioned chip too, the LF353, for the exact same reason we chose the 3875 - it has an almost identical topology, and almost identical response, just significantly lower dissipation.
Tried the burr brown efforts - nice but very HiFi, and Nuuks buffer is a treat.
As to the why this should work better than a TVC - I cannot give a solid explanation (I am not an EE by trade), but I feel that there are some input resistance variations (that are offest by capacitance to give a net input impedance), that take good old current to solve, and more than a TVC/Passive can muster.
However, the buffer needs only to have unity gain, and you'll add around 9 parts or so to the signal path (one way or another) - still a very low parts count, and it'll cost little to try.
Have fun
Owen