Well, I did try a bit more weight on the cart end, but I just settled on 12 since it was sounding good. Arriving at that weight was just a lot of trial and error, didn't happen overnight. I didn't think it would be a good idea to go too much higher, but never know, I'm always tweaking.
My thinking was more about a cart compliance problem than cart weight problem. It seemed to me that a stiff cantilever is going to need more mass or weight to trace the groove properly, more than a higher compliance or softer/springier cantilever. Before adding any weight, I increased the VTF and it seemed to help a smidge, so I figured the cart is not tracking like it should, needs weight, so that's what led me down that road.
But I wouldn't sweat adding weights. Besides, everything has a sound to it, it seems, aluminum, carbon fiber, even wood.