There's no headphone demo on us? What a shame. In Asia, there are many, China, Indonesia, Singapore, Japan, etc

Go for the momentum if you have enough budget. It's worth every penny. The momentum can even match sennheiser's HD in some aspects.

What about ath pro700mk2 ?

Yes, the ath m50 is a good headphone. But, you must try other headphone first before buying them. Everyone has their own taste of music. Recommendation, try m50, ath pro700mk2, ath es88, beyerdynamic dt770, sennheiser hd25-ii Ps: good thinking to sell the beats :D