mijostyn,
I have heard the arms you mention, and I have heard setups using these arms that did indeed sound very good. But, I would not make the generalization that a two-axis arm is superior in regards to bass reproduction (implying that uni-pivots are inherently inferior in this regard). As you noted, Graham makes a stabilized uni-pivot and so does Basis, and I think both are pretty good arms. If I had to pick a pivoting arm that had the biggest bottom end (and a very warm sound), it would be the Moerch Anisotropic arm, which is a uni-pivot arm with a low vertical effective mass but a very high horizontal effective mass that is specifically designed to be good at bass reproduction.