How do you build them? Did you setup an automated build?
I've written batch files for each compiler, which first pulls the new changes, then compiles every version and then automatically packs them.
Maybe I'll extend it, so it gets uploaded automatically.
Once you've configured it with CMake, building it "over and over again" is quite simple and fast in my opinion: "git pull" "make" "make install" (basically). It might even be faster than downloading, extracting and copying precompiled packages.
Yes and no, it's quite easy for one version but to build all versions you'll have to change the CMake settings etc.
I'm sure your packages will be downloaded mostly by beginners who don't want to bother with CMake
Btw if you want you could make this thread stick to the top...