cPFence Sorry for delay.
I'm not sure when I last used DirectAdmin but it offers complete isolation and I actually got everything I had with Enhance. The cPGuard is also quite attractive and easy for users to use i.e. the control is in their hands without having to fiddle with the console.
I can't say anything about protection because life has taught me that nothing is 100% secure. It is regularly checked by Rack 911 and it is initiated by DirectAdmin which makes me think they take great care in the security part.
Can you send me a case where a company was hacked because of DirectAdmin?