@LeGaulois: There is an almost countless number of exchanges which have better trade engines. Maybe they had some issue is in the past, but at least they fixed the issues and one can now reliably place and cancel orders without problems, even at the highest volume peaks.
Yeah you are right, keep using the exchanges that get hacked over and over again without learning how to implement proper security.
Also Kraken didn't only improve it's trading engine but also it's HW/performance.
I don't see things getting nearly as bad as last time ever again for them. But only future will tell.