I have used Poloniex over the years, it is a great exchange, like you said, I think this can only lead Steem to better prices in the near future as Circle may bring in a new change, like you mentioned exchanging directly to crypto, even if they do not make exchange open to all coins, it would still add great value to Steem being it is also on an exchange that does accept fiat. Just hope that through the process, Circle learns from what other exchanges have done, and makes improvements, and does not fail the customers.