Hi,
well i'm a Debian user, but since 64s is debian based, there's no
problem with the two repositories, so you can have both and download
the packages you need. I usually do that with an even worse case:
mixing lenny and sid repositories. I cross my fingers, and i only do
install ONE package i need, and after that i comment out the sid
repositories in sources.list.
Anyway you have to take care if some library is going to be
"overridden". In this case some apps looking for the old library could
not find the right library version, though i've never had that
problem.
Best,
Juan.