@alexanderglass you take on only additional risk by holding your coins on an exchange. There is already the risk of hacks, failures and disruption on the exchange, but in relation to Bitcoin Cash (BCC), if Poloniex decide they feel your current BTC should be in BCC, you can't do anything to stop it. We also don't know how long transfers will take (if not locked down by POLO) and how much they will cost, post 1st August.

If however, you hold your BTC in a wallet such as Exodus or Ledger, you can use your private keys to claim BCC and still hold your BTC. This gets you coinage on both chains as the history is shared between the two up till the split.

You should really start reading up on this as although I'm sure all will be fine, my best advice is to simply make sure your BTC is secured with you firmly in control of the private keys until after August 1st.

In summary:
• Get your BTC into wallet(s) where you control the private keys.
• Wait for the dust to settle after 1st August
• Do lots of reading so you can claim coins on both chains

Although replay attacks are being described as very unlikely or possible, be careful that someone smarter than the rest of us hasn't already worked out and prepared some form of hack that negates replay attack protection