Well I have had the XSP-1 for a few weeks now, sound and feature wise I can share some thoughts.
You can see my set up in the link below, not shown is the Musical Fidelity V link 2 and Parasound 2125 amp.
The speakers are Ascend Sierra 1 with NRT.
Sound wise, there is a distinct difference in the upper mids and Highs. The 2100 is more forward in the upper
range, Offering slightly more detail, and separation. I thought it was thinner sounding Than the XSP-1 in the upper mids. For my Jazz recordings (Diana Krall) the 2100 was slightly more engaging, Really nice, For Rock guitars I much prefer the Emotiva, The 2100 was thinner, And at spirited levels fatiguing , I never experienced this with the Xsp-1 And I never seen a review with anyone else experiencing that with the 2100 so maybe its just my room. Bass wise both are excellent, but I was able to really fine tune the crossover with my sub much better with the Emotiva, as you can adjust the range from 50hz to 250hz on the mains where as the 2100 is fixed at 80, which I did not care for with my speakers. Seems strange the 2100 has fully adjustable crossover for the sub which most subs have anyway but not the mains. Remote wise there is no comparison, Emo is full metal, really nice, You could hurt someone with this damn thing...lol...anyway you can not only toggle tone controls but change them from the remote as well. I stated earlier in this thread I thought the 2100 volume control was pretty accurate, others disagreed and after using the Emo I think they were right, I dont see how you can get anymore precise than this, it ramps up and down wonderfully and with the display the repeatability is exact. I couldn't be happier with this aspect of it. I cant comment on the phono section or balanced differential part. appearance wise the 2100 has a much lower profile and is overall more inconspicuous which I really liked. If I was using this in a home theatre setup the blue lighting on the Emo would be a dealbreaker for me. It has 10 levels of dimming but you cant shut it off all the way. Overall for my purpose and room, I am enjoying the Emotiva more so I did end up returning the 2100. Again, there is a 300.00 price difference between these units so its not exactly apples to apples comparison.