This is a real case happened with my friend on bittrex,
He's got hacked 10k USD, withdrew in BTC to another account. He cried it to the support team and guess what??? They replied with a sorry email including an activity report of his account.
SO BE CAREFUL GUYS...
Securing the account is not the job of Bittrex, securing Bittrex site is the job of Bittrex. So if your friends account was hacked then it's teh fault of your friend because your friend may have not used a password that is not so easy to guess and your friend may have not used 2FA to further secure the account.
I have been trading in Poloniex but was thinking of moving to bittrex. Would that be a foolish decision?
Why do you plan to move Bittrex in the first place if you have no problem with Poloniex? But I see no problem with using both trading platform.