Another interesting tidbit on patter mass comes to mind. When I bought my SP 10 MK II I was quite content with it. I came across a custom machined platter for it that weighed about twice the mass as the stock one, made of stainless steel as I recall. I ordered it and installed it. What I found is that the sound became smoother but was robbed of life. The table was fully capable of keeping accurate speed at the stock platter weight, and there was nothing of consequence to be gained from increasing it, matter of fact it was a step backwards. Perhaps platter mass does matter, but only within the context of what the designer envisions.
Why you did that ? You could just add Micro Seiki CU-500 gunmetal mat on top (perfectly matched). Here is mine. The weight of CU-500 is 2.7kg and it's 5mm thickness. That was huge upgrade for my stock SP-10 mkII.
When you're using not original parts, but some overkill superheavy custom platter why do you expect improvement ? Technics platter is already heavy.