I installed FC4 last night. Tonight I was doing yum upgrades. I didn't touch a thing. I just gave the command yum -y upgrade. Everything started downloading fine. 279 packages I think it was. Sound works, just plug in the speakers, no fiddling with anything.
I decided to reinstall though as the partitioning wasn't what I wanted. Not FC4's fault, it was mine. I should have paid more attention during the partitioning last night.
Other than the reinstall due to my lack of attention, I was quite pleased with what I saw. NO PROBLEMS.
Perhaps one of the key issues here backup your data, DO A CLEAN INSTALL.
I've been on these lists since ver 5.2 I believe it was. There are several others who have been here perhaps longer than me. I have NEVER done an UPGRADE. Always a clean install. I simply do not have the issues that I see people complaining about here.
I'm not trying to start a religious war here about you should do this or that. Or say that anyone is wrong or whatever. I'm simply telling you what I do and the results. YMMV
Mike