Personally, I prefer a Fedora to be short-term stable. What's the average lifespan of a Fedora release? From Alpha to EOL, we talking less than 18 months? That's not a long time to ask packagers and maintainers to maintain a package. At most you have 3 versions to maintain, and that's with a very aggressive release cycle.
I have the following options:
CentOS/RHEL: long-term stable for Servers and such.
Fedora: short-term stable for development, playing with fairly new features. Some stuff is broken (e.g. ATI OpenCL support). I run this on my desktop.
Rawhide: unstable for experimenting with bleeding edge features on machines that can be partially functional most of the time and non-functional for short periods. This I usually reserve for VMs.
I use each of these options. They all have their place. It does suck to have my email to get screwed up because of an significant upgrade to Thunderbird mid-cycle.
I really don't see a need for a midpoint between Rawhide and a short-term stable Fedora. Anyone who thinks they want this is really asking for "stable bleeding edge", and that is just oxymoronic.
I need something that I am comfortable running on as a primary OS on my desktop. With that I am able to provide valuable feedback to Red Hat and the Fedora teams. If they get too wild with Fedora, I will no longer be able to use it as a primary platform. I'll play with it from time to time. But I will no longer have the incentive to provide detailed problem reports.