I have both the XDS1 and the MPS5. The MPS5 is definitely not lean, especially compared to the XDS1.
The XDS1 did sound leaner at first but I've found that it does take a while to run in and it's very balanced now though without the mid bass emphasis of the MPS5 which I liked (I found the MPS5 similar to my Project RPM10.1 evolution/Sumiko Blackbird/Bel Canto Phono3).
But I do use a tube preamp which adds a lot to both the XDS1 and the MPS5, which I suspect is what you may be hearing with the tube mods on the Modwright.