I have both now for 1/2 a year, along with some others (notably DT 1350 and HD-25-ii (Adidas - regulars seemed too dull-looking)), used mainly with Tera Player.
Both are great phones, but I must say that I need to be in a particular mood to pick T5P over Edition 8: if I am totally fed up with pop music, T5P is the obvious choice. However, if I am undecided, I go for Edition 8.
The thing is that Edition 8 give me the involvement, immersion into music. And I can think about the music and seek the detail, or think of anything else (work, private issues, people on the street - you name it),- and still be immersed in the music.
T5P do the same and more for classical (and jazz), yet they become quite demanding with pop music. For the lack of a better word, - they are a nuisance. One must listen to them, and they wear the listener out. And if I don't really fee like it, I turn the volume down, - and they become clinical: the deep bass, which was moderate at its best, disappears altogether. And again T5P annoy me, - esp. when I recall that Edition 8 did not do that.
This being said, I am highly unlikely to sell T5P, as their performance with classical and jazz is outstanding. They just are not my daily beaters as Edition 8. If Edition 8 did not exist, T5P would have been my choice though.