Just got my XL pads in and swapped them out. Not only are they way, way more comfortable (glasses wearer here), I was able to get rid of all of my midbass-taming equalizer settings on Neutron & Poweramp. It really did rein in the bass quantity -- albeit with a pretty small loss of tightness. Bass impact seems to still be intact. Low bass/subbass seems to extend deeper as well. Neil Finn's "Into the Sunset" from One Nil is one track that benefits from the XL pad's lower bass extension and makes it really obvious.
Soundstage/digital imaging has certainly opened up. Sigur Ros's Agaetis byrjun sounds a lot less cramped, especially in tracks like Staralfur where the string and horn sections seemed to be too cramped in/on top of the rest of the instruments.
I liked their sound before, but not enough to keep from taking my Amperior as my standard daily driver. That might change now. Twenty bucks really well spent.