As a SysAdmin getting php.net to offer an official binary repository for the main Linux operating systems (Redhat, Suse, Ubuntu) rather than just source code would be the only way I would install a release outside of what the OS provider ships. It doesn't matter how trusted a third party repo is with the community when it comes down to things like PCI and legal; formal official support is all that really matters.
Manually compiling code massively increases the responsibility I have to take on and there is little pay-off for me or my team. 'yum update' compared to './configure ....' followed by sorting out support libraries that aren't compatible and then trying to compile again and again, its becomes a total none starter.
We only upgraded to PHP 5.4 on our systems because Redhat released a supported software collection that had 5.4 included. We'll look at PHP 5.5 soon but as yet they aren't offering PHP 5.6 so that isn't even being considered.