I usually listen to downtempo, nu jazz, deep house, chillout (lots of female vocals). I rarely listen to rock, metal, trance or drum'n'bass. I like the Sony's because they are the most natural sounding from the bunch. They are on a bright side of neutral and pair best with a slightly dark source like DX50. I actually was very pleased with that pairing. The highs are never piercing and the bass comes to play only when it is in the recording. At first, I thought they were bass light and I'm not a basshead by any means. I'm actually very sensitive to too much bass. Then I played Ott - Mr. Balloon Hands and, boy, did I get some bass. It was very textured but never overpowering. In addition, I found the soundstage very pleasing and not cramped in. I'm a strong believer and supporter of EQ. However, I don't find it necessary with the Sony's. Basically, I didn't find anything bothersome about their sound signature.
In terms of comfort, they are also the most comfortable headphones from the bunch. I would rate them on the same level as HD6XX series. I was a bit disappointed in the HP50's headband construction. Depending on your head shape, it may cause minor discomfort on the top of one's head. Also, usually I don't care much about headphone's aesthetics. If they sound good, I don't care if they make me look like Princess Leia. However, I would think twice before wearing HP50's in public. They look a bit dorky. Please don't get the reds. The color doesn't look like anything in the pictures. It is blood red and not burgundy red.
For portable use, they are a bit big. The drivers are 50mm plus the cable is way too long. For portable use, I would go with Momentums purely based on their size and design.
Well, the long cable is not really an issue if you just get a shorter aftermarket cable. It uses standard 3.5mm jacks, so cables are very easy to find. That's what I did, for 5 bucks.
Otherwise I second your opinion on the 7520, although I'm not sure if I would call them bright. But to put it differently, they're certainly not dark and they're very very clear sounding. I was very impressed by the clarity and I also tested many of the headphones you tried, which all sounded veiled compared to the 7520.
In terms of music genres, I listen to rock, alternative, modern jazz, electronic (that includes EDM, but also more downtempo forms of electronic music), reggae and some classical music. It all sounds very good on the 7520. Very detailed too, towards the analytical side, but never without losing its musicality. I especially think guitars sound gorgeous on the 7520 and the 7520 has great imaging too.
And in terms of comfort they're the most comfortable headphones I've tried so far. Only issue I have is that the earcups aren't super deep, so my ears touch the drivers a bit. This can be *fixed* by thickening the pads by putting some cotton balls (stretched out that is) underneath, but I noticed that it made the bass boomier, so I've decided to not mod it and just leave it as it is. I only notice the discomfort on my left ear after about half an hour, and then another half an hour later it's mostly gone as I guess my ear gets used to it (and it's just very minor discomfort).
Anyway, I highly recommend you give the 7520 a try if you can get your hands on one (they're rare here in Europe).
Oh, and in terms of portability, they don't fold flat or anything, but they're not too bulky either to bring with you. And it isolates pretty good. Just make sure to get a shorter after-market cable. And I like the understated utilitarian looks, but that's just me
