Hey mate, while I used my friends H8P for a good duration, the fit was obviously not optimal. However I was pretty sure of what I am hearing. Now I can't really explain why the Pro has totally different tonality and unnatural feeling, considering what Peter said, it has to be something with treble tuning. Would it matter that much? I honestly don't know but my ears says yes, it has an affect on whole spectrum.
As for the tonality of mids and bass compared to the SE5way, I agree, SE5way has the richest and most organic taste. On the bass, I don't think H8 lacks the quality but their presentations differs a little bit, especially how it surrounds the listener. Mids are totally different story though. I think SE5way has the edge on the quality but their presentations are waaaay different. H8 just spacious and envelopes the listener while putting the stage laid back, SE5way has all the same details but it puts them all right in front of your face, very close with a slightly brighter tonality (especially upper mid) in a pitch black background. I don't say it is bright, it is just, the background and stage feeling is so on point and very silent, every instrument has its own shining area, thus creating a fake brightness. It is a very clever and successful tuning if you ask me, while keeping the warm and organic tone but adding s*it load of details and transparency.