Much to my surprise, I got my Circle account shutdown after I tried to purchase a whopping 0.1 btc which was supposed to be "instant" and just sat in a pending state until the next day when it was cancelled by Circle and got this love letter from them the following day. http://i.imgur.com/s8bewO8.png
I've been using Circle for quite a while only purchased relatively small amounts ( < 1 btc ) and only every 1 or 2 weeks and never sent it directly to a DNM. I always used 1 or 2 intermediate wallets, but it was to no avail. I did not use a tumbler, but I'm not even sure that would have made a difference. Ironically, on the same day, Coinbase upped my instant purchase limit :-)
Worse than a bunch of fucking nosey neighbors. Fuck circle, fuck coinbase. LibertyX all day. You can stay anonymous and they don't give a damn where you send YOUR coin. It's as easy as buying a pack of bubble gum at a gas station.