For hosts offering shared hosting biggest challenge is to limit resources for each domain/customer. Most of small hosts and startups fail to achieve this which results in sudden spikes in resource uses by a single, tacking over whole server and resulting in support tickets from other users on this server. Cloud Linux the solution to this long standing problem.
Cloud Linux is specifically designed and written for web hosts running doing shared hosting. If you are looking to host more clients and still offering high stability, less reboots and more security CloudLinux is what you need. It is interchangeable with centOS and will fit with most commonly used centOS/cpanel combination.