I believe that modf is now ready for public testing and usage, so go ahead and give it a try. Its dependencies are just Alexandria and Closer-MOP and FSet if you want to use that library. It is broken into a main Modf library and an FSet add on library. FUNDS support is going to pushed to the back burner because after looking at it, again, it seemed kind of under documented and annoying to deal with. Plus, my experiences with FUNDS vs FSet has told me in the past that FSet runs quite a bit faster than FUNDS, so is probably preferred by the community anyway.
Edit: I went ahead with the FUNDS support, but it isn't really much. Unlike FSet, FUNDS doesn't intend to be a replacement to the fundamental Lisp types. Most FUNDS data structures do not include the ability to edit arbitrary elements. FUNDS has trees, and Modf functions are defined for those, but the queue, stack, and heap data structures don't really make sense with Modf. You access them in a different place than you add elements.
This library is small, but kind of reaching completion. Any suggestions or patches are welcome.