I am a vendor on MEM and withdrew last night. It did not go to my account immediately, but I did receive it today. I am not sure why it took so long...perhaps the upgrades they were working on?
I had a problem with MEM withdrawal about a week and a half ago that remains unresolved, but have had two successful withdrawals since: https://www.reddit.com/r/DarkNetMarkets/comments/3q60xp/mem_withdraw_problem/
I also made a withdrawal last night from MEM and didn't get it in the other wallet until sometime today. This gives me hope that they are dealing with updating the site and not just peacing out.