First of all I am comparing release versions. Thus the unstable branch of Debian is somewhat irrelevant; yes: Debian Sid is usually more up to date than anything. It's closest analogy is Fedora Rawhide. And more or less famously: the question of “how do you run it?”, is answered with “you don't” [that is the Debian wiki, not me]. These are not real distributions: these are dumping grounds for new code to be tested.

Now, when it comes to *release* (supposedly: *stable*) versions: Ubuntu, or at least, Kubuntu is certainly more up to date than Debian Squeeze is. When I had KDE 4.4.2 on Kubuntu, I'd have KDE 4.3.4 on Squeeze (testing). KDE 4.3.4 was 9.10 material for Ubuntu. As I said: Ubuntu is in between Squeeze (testing) and Sid (unstable), with the early alpha being mostly Sid and the release being closer to Debian testing.

The proprietary ways bit comes from a lot of `fun' with ndiswrapper & fglrx, including but not limited to unrecoverable installations. YMMV. The bit about manpages is probably clarified with a simple `man xorg.conf'. Similarly, polkit/policykit have man page entries for their configuration as well IIRC. Of course, you do not have to configure your system. But my point is: if you don't want to do the configuration dance then maybe Ubuntu is not such a bad option -- it comes with mostly sensible defaults and a considerable later crop of software out-of-the-box.

Ubuntu (LTS or not) does not intentionally receive any update that `breaks' the system in the way you mention it. Have you actually *used* Ubuntu? I ask because if you had used it you would know that the Ubuntu repositories are most definitely not the Debian repositories, that you should not even attempt to mix the two (barring some very specific apt.get wizardry), and that there is such a thing as a “Debian Import Freeze” and it is before the first alpha is released. You will, therefore, never get your updates directly from Debian Sid or testing if you run a release version of Ubuntu; and Ubuntu LTS means that you get updates on your software for a longer period. Also LTS releases are based on LTS kernels which typically means the kernel of (next) RHEL. In casu 10.04 ships with 2.6.32 for that reason.