1.) In the last 30 minutes, I have moved Dash from Polo. No problems. Never tried to move cash. Usually, moving coins is no problem. There have been issues moving coins in the past. Mostly it was just system issues. The only time I ever felt scammed was with the bail-in in March, 2014. Note: fees on transferring some coins are pretty high. NEM, for example, was too high the last I checked.
2.) Polo has staff????? Fuhgetaboutit.
3.) Not in a long time.
4.) Very liquid.
*I have only had what I would consider large amounts on Polo twice. The coins were then quickly moved.
Most of companies have issues all the time but they can be resolve it by a very good customer services and also there responding time.
I would agree.
All crypto exchanges have customer service issues. The only exception, in my experience, is SFOX.