As far as I hear Poloniex does not stake the POS coins (unfortunately, I forget and can't provide the source of the info), neither does BitTrex, I think, but better ask them directly
I heard (in the
Ambercoin thread) C-Cex does stake. And I am affraid Bter does the same.
For the coinholders it is better to trade their coins on the non-staking exchanges.
I totally agree with your thoughts.
I'm not a big advocate of even holding coins on an exchange - once your done trading, withdraw immediately.
But as history has shown time and time again, that even after exchanges get hacked over and over, traders still end up leaving their coins in them for extended periods of time.
With that in mind, we might as well work with what they want. Yes, you are right Polo and Bittrex do not stake POS coins at the moment, but that's because they are afraid to because they would increase the exposure of these wallets to outsiders wanting to hack them. They would be deemed 'hot' wallets because they are online and running in order to mint new coins. They don't want to risk the possibility of their reputation if someone hacked their system. Once hacked, the first thing the hackers would go for is the 'hot' wallets. So for extra security they maintain their wallets in cold storage or offline. These can still be hacked buy in my opinion it typically can only be done by an insider in the exchange.
So the whole point of my post above is that with BitBay, it's unlike 99% of the other coins out there, as you are capable of using 2 private keys to access and run 1 wallet.
So this gives a lot more options to the user. Not only can these keys be encrypted with separate passphrases, David's added steganography to the client, so you could essentially hide the encrypted private keys inside images. With 2 private keys you can create joint accounts. Joint accounts would be no different than 2 business partners running a business and each partner has a key that unlocks the door to any funding they need to conduct business. It makes it impossible for 1 business partner to 'steal from the cookie jar' without the other's permission because the cookie jar has 2 locks on it.
Joint accounts don't have to be for 2 business partners. You could essentially create a joint account for yourself.
With this in mind, here is an example of how tight the security of BitBay really is...
You could essentially passphrase protect one key, hide it in an image and store it on a laptop. The second key is also passphrase protected, hidden in an image, yet stored on a raspberry pi.
So in order for someone to hack your joint account wallet, they'd first have to simultaneously hack both computer devices. Then locate the images with the keys inside of them. Then crack the passphrase that protects the private keys. I'm not saying that anything is impossible in the world of hacking, but I'm sure you could ask around - this wouldn't be easy to do by a long stretch!
Now with that in mind - imagine applying that to an exchanges cold wallet, hence why David calls it 'cold staking'.
The exchanges wallet could be 'hot' yet it's a joint account setup and only 1 key is hot while the other key cold and hiding on another computer device.
This could most likely only get hacked by an insider.
So yeah, polo and bittrex do not stake coins because they are afraid of exposing the hot wallets to hackers, but with BitBay's Halo Client, now they have a way to stake them and it would essentially be no different from still calling it a 'cold wallet'.
So why not stake and retain the rewards for profit?
I hope that clears things up for you. This is just one reason of many why I'm very bullish about the future of BitBay.