Inaccuracy on Custom Download web page

On your custom download page under the Linux section you say that the version
available rarely coincides with a distribution release. That is true for most
of the Linux distros listed, but not for Arch Linux. Arch always has the
latest distribution release available. That's one of the main points of Arch
Linux ;-). In the case of Musescore it's in one of the supported
repositories.
The current git checkout is also available in the Arch User Repository
(unsupported).

I suspect that Gentoo has the newest version always as well, but I'm not sure
about that.

May I suggest (yes, I like Arch ;-):

Linux
Distribution packages

Many distributions release a package of MuseScore with each new version of the distribution. However, with the exception of rolling distributions like Arch Linux, MuseScore releases rarely coincide with a distribution release so these packages are often out-of-date.

Arch Linux: The 'musescore' package is always the most recent release version of Musescore. Just run "pacman -S musescore" to install and then use "pacman -Syu" to keep up-to-date.
Ubuntu: Search for "musescore" in the Ubuntu Software Center.
Mint: Search for "musescore" in Software Manager.
Debian: The package "musescore" can be installed from the main repository using your favorite package manager. A more up-to-date package is often available in the "unstable" (sid) distribution.
Fedora: Check your package manager or run "yum install mscore" as root.
Mageia: Download the correct RPM package using Mageia Control Center.
PCLinuxOS: Available in the PCLinuxOS repositories.
Gentoo: Available in Portage. Just run "emerge musescore".

Community packages (usually up-to-date)

The MuseScore community may provide a more up-to-date MuseScore package for your distribution:

Arch Linux User Repository: Install the latest git checkout 'musescore-git' alongside the release version following directions on the Arch Linux Wiki
Ubuntu and derivatives (e.g. Mint): Add the mscore-stable Ubuntu PPA. (Instructions on that page.)
Debian: Check the "unstable" (sid) distribution, or you could try manually installing DEBs from the Ubuntu PPA.
openSUSE: The latest RPM packages for openSUSE can be downloaded from the multimedia:musescore2 repository of the Open BuildService. The easiest way is to use the 1-Click Install (click "Show unstable packages").