Okay... So I did some more digging and found this thread in the forums:
https://forum.step-p...ni/#entry144396 (last entry: 31 Oct. 2015)
The best answer says that the Occulsion Culling in SPO does it's work within the context of the game's engine, while ENBoost does it's outside (read: on top of) the games engine, but has some issues and is thus turned off. Although the "EnableOcculsionCulling" parameter isn't disabled in ENBlocal.ini, I think I may change it to false (in order to see what effect it has, if any), and just let ENBoost do it's memory thing. I've done some testing with my loadorder/modlist (145 mods/171 esps) and I'm getting solid 60's both indoors and out. I couldn't be more pleased with that.
Unfortunately, I had to let ENBoost go. Not long after this post, I went back to my test character and immediately started getting hitches, stutters and the dreaded CTD! Once I removed ENBoost and even added more mods in the process my game returned to it's previous level of stability, quick loading screens/transitions, minor (1-5) and quickly resolved fps drops but overall solid 60's indoors and out. I'm watching the amount of RAM used via Skyrim Performance Monitor, and I've topped out at around 2200MB (in combat, multiple adversaries). Naturally I'm keeping an eye on this, but either way, I couldn't be more pleased.
[Caveat] I don't use any enb, because... my preference. I'm content to use Realistic Lighting Overhaul, Imaginator and texture mods (not the official) to improve the look of my game. Perhaps I'll revisit this when Skyrim Remastered is launched. I also turned off anti-aliasing and anisotropic filtering via the game engine and just let my GPU (GTX 970 4G) handle them.