Polo was my favorite exchange until the verification regime...
But it has survived primarily by going all-in on XMR... and a few other creative Asset listings (MAID, STORJ, NXT)...
And that Troll Box Pump Machine.

For most coins Bittrex has better liquidity...
But trading both exchanges is significantly more profitable because you have 2 spreads to capture.

Frankly, I don't expect these exchanges to survive once FinCEN turns the screws on Alts...
Doing about $100,000 to $300,000/day in volume sounds like a lot...
But that's only about $500/day in fees... add listing/trading... maybe $500,000/year in revenue.

If Cryptsy really has 40-50 employees they are probably losing money....
And you can work 24/7 and break-even only for so long... then you must pull the plug like a lot of defunct exchanges.