[jnxx]

> I really do want to do this, precisely because the software in the repo is often out of date,

That depends much on the distribution you use (if recentness is most important, why do you don't use Arch), and being out of date is definitely not the case for Guix System:

http://distrowatch.org/dwres.php?firstlist=guixsd&firstversi...

Sp, why are you bringing an argument that does not apply to Guix?