Ok... So I wiped the computer clean. Installed JUST Mavericks, Resolume (latest Avenue version) and the last IRMapio. Rebuilt the set from scratch. Took me about 4 hours, but it was looking nice.
Crash reports: Resolume crashed a few times when I was simply dragging video files over. That was a bummer.
Otherwise, everything was working fairly well, as I was used to anyhow in 10.8 on that same machine.
Then - IR Mapio time. I reinstalled it, mapped one of my layers (no problem), tried adding it to another layer - and everything froze. The layer it was added to disappeared. I could still somewhat use Resolume (albeit very sluggishly). If I deleted that IR Mapio instance - everything re-appeared. But adding a IR Mapio instance would inevitably crash everything. I downloaded several versions of IR Mapio (Visution as well). Nothing worked. Alas, no time to try Mapio2. I just bought it, installed - but learning how to make it run as a plugin was complicated for me to give up on this path and use my personal computer with 10.8 to run the show yet again.
Also - Mavericks by default - displayed a finder / other menu bar on the secondary display. To remove that (it was a bit nutty on top of all my issues), I found this helpful blog:
http://www.mactrast.com/2013/10/disable ... mavericks/
My summary:
While Resolume is not perfect, and it does occasionally crash (i.e. loading files) in Mavericks, my biggest culprit is likely the older versions of Mapio (1.5, etc) plugin. Which, for me anyway, straight up didn't work in Mavericks. A bit of a stressful thing to try to learn on the fly in the middle of a tour, but that's what it is. We had to upgrade, since a new set of cameras we got, required an OS higher than 10.7 for that computer. And since Apple didn't offer a 10.8 anymore - we risked 10.9 ---> and regretted it. A lot. Hope someone can learn from this and not repeat my mistakes (if you have IR Mapio - DON'T upgrade the OS).