Where I live, the Major FX is about USD70 more expensive than the V55.
Can I just say, I find the V55 very disappointing. It doesn't sound good, but it doesn't sound bad either. The sound is just blah, bland, ambivalent.
Personally if I had money for a V55, and want a Sony, I see two options.
I could spend less and get the cheaper XB400, which features a much better-looking headband (no gap between headband and head), and I would use EQ to reduce its extra bass.
Or I could spend more and get the MDR-10RC, which is $150 in my area and guarantees a certain level of quality.
Most, if not all Zound Industries headphones (Marshall, Urbanears, Coloud etc) are geared towards EDM. If you listen to a lot of EDM they should be okay, but again none of their products have really impressed me with sound. They always sound good enough on their own, until you audition something else, and that something else will invariably bitchslap Zound products all over their handsome earcups.
Personally at the price range of these two headphones, I'd be interested in the Creative Aurvana Live. If you need isolation or just want a new product, Creative's got the MA2600.
These are just my opinion, and I would really suggest you audition both if possible. You might find that they're more than good enough for you. Happy shopping.