Specifically for coinmarket.io, I personally think the guy operating this exchange is faithful and there will be an explanation for the trouble. I can not see a reason for him to run away. He will make much more money by keeping it running.

But you never know. I trade always with smaller amounts, even if I have to send 5 times. And I don't use exchanges as my wallet. Independent what is the name of the exchange.

btw. I also don't trust banks in real live.