Here's a post about another Steemian's experience with Poloniex:
https://steemit.com/poloniex/@dwinblood/poloniex-great-fees-great-graphs-which-are-worthless-if-they-keep-your-money-or-don-t-move-it-quickly-enough#@tanyehwen/re-dwinblood-poloniex-great-fees-great-graphs-which-are-worthless-if-they-keep-your-money-or-don-t-move-it-quickly-enough-20170605t172834861z