Well,
I'm a recent convert from WBEL. My biggest concern with CentOS is that the community here seems to want to be more than a recompile of RHEL.
But WBEL is floundering, what with Katrina and Rita, and there really being only 1 developer behind it, etc.
I offer an automated shell script to switch from WBEL4 to CentOS4 (easy, it's hosted on my home DSL line!) It assumes that you've been using yum to perform updates...
http://chico.benjamindsmith.com/wbel2centos4.sh
How many otther ex-WBEL users are there here?
-Ben