However, the increase in complaints at least justified to do a trial balloon first. So I decided to first deposit a few ETH to Poloniex, do some trades and then withdraw my funds as ETH, BTC and XMR. Just to get an impression in how smooth the workflow on Poloniex is right now.
And know what? My suspicion was well founded! The deposit didn't make it through! It's not showing up in my Poloniex account, neither on the balance page nor on the deposit history page. And of course I sent more than 0.5 ETH to the correct ETH deposit address. Hours passed since the transaction and it has now 500+ confirmations on the Ethereum blockchain - but still nothing.
After years in Cryptos I had many problems with frozen accounts, delayed withdrawals, hacks, scams and bankruptcies. But a missing deposit is new even for me.
i'm now hearing so many of these complaints across different mediums, that i'm now becoming very concerned that this is cryptsy 2.0. this time, way more money is on the line.

On the other hand, despite the answer to my support ticket being really polite, it reads like a copy 'n' paste they send out on a daily basis. And more important: My funds still haven't been credited to my account.
exchanges do this for days and weeks on end without making any effort to begin resolving the situation. i received 3-4 such boilerplates over 7-8 days from coinbase the last time i had an issue. when a real person finally responded, they basically ignored my emails and were obviously still referring to a templates of boilerplate answers.
from the sound of peoples' recent experiences at poloniex, it could take weeks to resolve even this small deposit situation. if it gets resolved at all.