I'm curious as well. While I haven't upgraded any older projects, I started a new project on 3.1.rc4 several weeks ago and (besides deprecation warnings for some testing tools) have had very few problems that grabbing a newer gem couldn't fix.

There are significant changes that I wouldn't normally have expected in a point release.

To your point, the community has rushed to support many of these changes so it's unlikely to be a big deal.