The Variax standard looks pretty much like a yamaha pacifica. Hi have both a jtv-69 and a yamaha pacifica. I love my pacifica, after having done several changes to it but the most important one was the trem block. The original one was a flimsy zinc block. Once I changed to full-sized steel piece it the pacifica became another instrument: the tone shines and has sustain.
IMHO, it has nothing to envy from the JTV-69 (guitar-wise) - in fact it has more sustain.
There is a huge difference in the neck, both good, very thin in the yamaha. It comes down to personal preference.
Now, the problem with upgrading a variax trem block, is that it contains the piezo electronics, which closes the door to aftermarket parts and I would anyway never dare to go mess with it.