I'm not confusing the XPS/XPS2...I owned them both and for several months ran them side by side into both a CDS2 and a CDS3 so I well know how each power supply performed with each CD player. I have also at a friends house compared the XPS1/XPS2 with a CDX into 52/500/DBLs. And the XPS2 is more than marginally better than the XPS1, but mostly in the midrange and upper registers, where is it cleaner, more textured and subjectively less noisy.
And I also compared the XPS2 with the 555PS on several occasions too, using the CDS3.
I haven't heard the TeddyXPS- I expect very few here would swap out their 555PS for a TeddyXPS, probably for reasons more psychological than anything else. You have to admit that the cost, reputation and weight of the 555PS confers a certain pride of ownership. And for many high-end Naim owners, that cannot be overlooked.