Regarding volume, I tried to register for Bitstamp a few months ago, and it asked me for a scan of my passport and social security card.
That's not only a no, it's a "Fuck No".
That with the rumored difficulty of withdrawing, Bitstamp's KYC procedure has effectively killed off its volume.
That is not rumored, i personally know a guy who tried a withdrawal 2 months ago which has been cancelled for no reason after 1 week. He finally got his money after 2 weeks, but it was just a couple hundreds $. This story plus the questions they ask retroactively whereas they are not legit are enough for me to be sure i will not trade there. But dear daytraders keep waiting for the volume to be back in Bitstamp within this new framework.