Do we have the volumes of inputs and outputs for different coins on Poloniex ? I would expect BTC to dominate, and BTC deposits/withdrawals seem to work fine. I have again made several BTC deposits and withdrawals today, very quick, hassle free.
Withdrawals are broadcast almost instantly, no other service I've used is that quick.
I think mining is now popular again due to the btc price. Huge amount of newbies mine direct to the wallets of exchanges, and poloniex just cant cope with this