From time to time distributions such as Mandriva, openSUSE, Gentoo get some attention through some features they introduce, Speedboot, control centers, first to include KMS etc. What I believe these guys miss is that the availability of software is the biggest problem some user might face.
1.Debian/Ubuntu and RedHat (and Fedora more or less) get most of the attention from closed source packagers.
2.Point 1 applies to open source packagers that don’t have resources to produce packages for all the Linux fauna. Not all software is like the kernel or Firefox to be omnipresent.
3.Even if the software is not available for the likes of Debian or Fedora, because of their high penetration, the chances to find an article on how to make things work are high.
Mandriva is not going to cut it unless you are in a well established setting, where you are assured to need nothing more than the available packages. I remember switching from Mandriva and SuSE to Debian and notice how it suddenly becomes possible to run all kind of software. I cannot imagine testing all the things I needed with anything else that a Debian or RedHat system.
I would suggest Mandriva to try to move all its technology to Debian-like packaging and make the system 99.9% percent compatible with Debian.
„Mandriva offers you 5 seconds boot time, super-duper control center, x kernel enhancements and the already proven Mandriva technologies combined with the possibility to install any package available for Debian”.
So this is far-fetched, they have RPM knowledge etc. Replace this with Fedora. I just chose Debian because of the primitive (in my view) packaging system that Fedora offers.
I don’t know the disadvantages, but the advantages are obvious: one less target for independent packagers, access to the whole of Debian software and one more step for compatibility between distributions.