Only a few comments from who as myself follow the developments of RPM5 from 4 years now and sometimes, not as myself would like, is involved in the development, thanks to Jbj (http://rpm5.org/team.php ).
In any case perhaps it is a little know fact that also the major distro that use @rpm.org have a big pile of patch not upstream : so maybe the fork of RPM is larger than what you can think in general. Always on this point, Jeff Johnson asked all to join rpm5 in the past on the now defunct rpm-devel mailing list https://lists.dulug.duke.edu/pipermail/rpm-devel/2007-Jun... ):
so was not a choice of rpm5 that rpm development today is based on a competitive model and not on a cooperative model.
Regarding the documentation I can be partly agree, but this was not considered in the past as a impediment on the development of rpm5 (in fact see my comment on this http://trainofthoughts.org/blog/2008/04/14/rpm-51-released/ ): today it may be more important, in my opinion, given that Mandriva and other Unix/Linux distro belenix, openindiana, IDMS ecc. - has decided to use rpm5: FWIW this is in my todo list for sure.
For example we at @rpm5 started writing FAQ on launchpad, and myself included will try to update the rpm5 documentation, as my time permit.
As I said rpm5 is also on launchpad, one of the biggest platforms for the management of open source projects,thanks to a beautiful idea of Jeff Johnson, as always:
with this @rpm5.org automatically track the rpm bugs or generic problem by many distributions, here we have blueprints, FAQ, questions, answers.
So not only the mailing lists. For who is interested look here:
In fact RPM5 has a process of continuous integration, with buildbot for many distributions (take a look a O'Reilly Beautiful Testing for all of this), and all this with very little funds, little resource, with much difficulty, only thanks to the enormous and sustained effort of a person and with the help by some little other.
Just for example, i myself personally know that one of the biggest Italian bank are using RPM 5.1 in production on AIX and Solaris
and @ rpm5 has already offered support to IBM to migrate to the prehistoric version of RPM on AIX this @rpm5.org offert is always valid for everyone distro, UNIX vendor, i am pretty sure.