I wont post what i think of Fedora here i will create a new post to give my recent experiences with it. ( It will not be a positive post ........So Fedora fan boys dont bother reading. I am not trying to start a ditsro flame war it will just be real world issues & experiences so it will be all fact based)
But you comment about running different repos concurrently isnt really true......
You need to install & set up yum-priorities (this will be in your distro's base repo fedora/redhat/centos etc) in yum so that you dont end up getting in a mess with packages.
Also worth looking at setting up in this scenario is yum-fastestmirror both are easy to setup if you want i will post a basic tutorial. But just google and you will find loads of How-To's.
I hope this helps.
Edited: ooooh i just spotted the date of this post after i wrote this........but it looks liek some life needs to be kicked into the Linux section of the Forum.