It really depends on what you like/dislike about the he-560, and what you're looking for with the senns. It also depends on what your current gear is as well. IME, amps that work well with the he-560 (speaker amps) won't work well with the senns (OTL tube amps). Of course there are high end amps that handle both types well.
HD800 for listening to non-anime/doujin music. TBH, it's kind of a waste to get the hd800s if you mostly listen to that stuff like I do. That's why I sold my pair a while ago. Now if I had a nice EC amp to go with my yggy, that might be a different story xD.
HD650 is great for just about everything, when paired with a revealing amp and dac. Smooth throughout the whole FR, and a touch of extra bass for some fun factor. But at the same time, they are very resolving for when you want to listen to well recorded music.
After spending some time with the he-560s, modded and unmodded, I just couldn't take the treble with most of the music that I listened to.