Del,
I too own both the SuperDual and SuperMacro, but I would not say that the Macro is a big step up like goto, but it's definitely a step up and worth every penny. I have one of Xin's earlier Macro's (pre-release) and I would say the bass boost is not as deep as the SuperDual, at least not now. I have sent my Macro back to Xin for the new modifications he has made to the bass boost for newer Macros (6db --> 10db, I believe), so I'll have to wait for any comparisons between the two boosts.
All that being said, I think the Macro has better highs, a wider soundstage, better extension without bass boost, and an edge on clarityand a real clean sound.....like being almost in the front row! But, my goodness, the SuperDual has some really fine sonic merits. It's a tough call for me.
To tell the truth, I was thinking about selling my SuperDual, but I am not so sure any more. They both sound amazing for their size. I'll probably use the Macro and SueprDual interchangeably for a while (my SuperMini is permanently attached to a Xin-modified Sony SR84 radio.....Xin has the title to my house!), and I'll wait and see if the I'll put the SuperDual up for sale.
Hope this helps.....some.