@2channel8,
My experience is that a Basis Vector 3 substantially outperformed a Rega 600 tonearm. I have owned a MMT in the past, and it was about on par with a Rega. Maybe one of the greatest improvements I made to my system. Everything was better especially the imaging and image stability/specificity.
I would not hesitate to upgrade my tonearm if I were you. Basis makes a great 9 inch tonearm. If you can find one used it can be a real bargain.