My company used to use CentOS on our servers, but dropped it a while back specifically because its SELinux implementation was broken and kept causing all sorts of trouble for apache.
If I may: 1) CentOS is a clone of Red Hat, so if there is a problem, you are blaming the wrong folks. 2) There is an active volunteer army of support people on the mailing list who can provide details and help if need be. I am new to Drupal, but the support and cost ($0) seem similar, and both seem to be great products that work great together. http://lists.centos.org/mailman/listinfo/centos 3) SELinux is to me a complicated security system. It can be turned off, Google for (turn off selinux centos) or set to warn only.
If you're having trouble with other PHP apps, too, then I would definitely put the blame on SELinux/CentOS at this point. SELinux is hard to get right unless you really know what you're doing. IME, CentOS does not. :-)
I have found CentOS to be extraordinarily great software that is well supported and stable as a rock.