Darren
I know the Koetsu's luv mass. I had a 3gm headshell weight on prior to using the 2gm isolator. The added mass has nothing to do with the big change the isolator brought to the musical equation.
I have also played around with blu tack extensively, on the headshell and strategically placed along the arm tube. It does make a differences but only in certain frequencies and is cartridge dependant. It added bass weight to my system, however also made the tempo more clumsy and lumpy with the koetsu.
The isolator changed all the frequencies for the better and has made the top to bottom coherence so much musically better.
funny I have now received my 2nd isolator to put onto the other arm wand with my dyna xv-1. BUT I am in no hurry to do it. the system is sounding that nice with the isolator/koetsu combo.
Anyway, it is very easy for all of us to be critical of something seemingly simple that many of us can "somewhat replicate" at home.
For me proof is in the listening and the isolator is THE BEST $150 I have ever spent on my hi fi.
With all the money we spend on out hi fi, especially cables and tweaks, the $150 on the isolator is trivial if it works in your system - like it has for me.
cheers
Shane