OK, I've been testing out the 64bit RC by doing the following:
1 Compiling software outside of the slackbuild system (i.e configure, make, make install)
2. Installing multilib (via djemos script)
3. Removing multilib (via a third party script)
4 Repeating 2 and 3 via various methods including manually
5 Downloaded, compiled and installed a gigabyte (or two

) of software through gslapt/sourcery
6 Removed packages, re-installed packages, upgraded packages.
7 Tinkered with runlevels, rc.* scripts, xfce settings, sudo rules and lots of other things that are best left alone
8 Added latest versions of some of my "must-have" stuff, as well as commercial packages.
and we're still running smoothly.
While a lot of the stability is due to slackware, the care and attention to the Salix additions is evident to me after doing enough to bugger the 'buntus, frazzle the fedoras and raze the red-hats
This has the feel of a rock solid release to me.
Thanks to all the Salix devs, contributors, packagers and testers.