I am having no problems with any plugins I'm using paid or free. The good designers tend to update their plugins very quickly after a new release. I think it would be harder to find a good/popular plugin that wasn't updated already than one that was not.
I updated my blog the day 2.8 was released and I have not had any problems. All of my plugins worked with no problems, no problems with the theme - everything went great.
Right now I am working on wp 2.7 and didn't updated to latest version of wordpress . My designer is not online from many days and I don't know that theme will work fine or not on latest version , so I am sticking with 2.7 .