The VPI weighs (about 5 lbs total weight) much more than the brass one in the above link. It fits snuggly to the outside edge of the VPI platter, so it is very centered. It helps warped LP's only a bit (in my experience). I don't feel it is a PITA, but that's me. A couple LP's I own circumference is too small to allow you to use the PRC (2 out of 4-500 approx). I have no experience with the TT brand PRC above, though I am considering a TT brand center weight.
I realize this did not answer your questions, but I still hope it is helpful...
I realize this did not answer your questions, but I still hope it is helpful...