I'm actually running Debian with Sid installed (I would be running Ubuntu if it wasn't for the delay between their respective releases) . Its kind of sad that Ubuntus main benefit (since Debian experimental releases are too wild) is that its everything you like about Debian Sid....great support; almost cutting edge, with backported fixes for stability(although not as Stable as Debian stable... but that is not cutting edge) with some sensible defaults...because it is basically Debian Sid.
Hell I quite like the fact that users tried to make Debian pretty (and fast).But the move towards recreating elements rather than *selecting* popular ones (Mer seriously) like say KDE 4.8 Oxygen, is going to hurt them. I hope they have success with Qt... where I think KDE (and all the other garbage...like a new package manager) might be a better fit.
So yeah not obligatory...I'm using it with KDE now, and accept other roots when I use that (and GNU/Linux)
Not is someone could go about producing a rolling (cutiing edge) GNU/Linux release (with an enormous rescue me button) then I would look forward to it.