I never looked at these things. In fact I try to avoid pretty much everything thats fancy and based on something thats more original.
My experience has been that we are not limited by CPU/Memory. Yes there are cases where we have hit the ceiling , and may be there are some use of extra CPU/Memory. But 99% of the time we are actually struggling with neat features, reliability, documentation etc. Put other ways, my personal focus has always been to get the story right, i.e. get a functional controller running that can does the daily chores of reef keeping and can be built by most DIY enthuthiast. Sticking to original Raspberry Pi and avoiding most fancy things helped me achieve that, as I ride on the shoulder of those giants. We get to use standard raspberry pi/adafruit community help, and continued software improvements. This does limit us in some way, but I think its worth the compromise. Its ok to not be able to run both webcam and the entire controller in pi zero, as long as it can does the main controller bits, for each of us, easily and forever without hiccups.
In the very beginning when I started reef-pi development, reef-pi was named reefer and I was aiming to make it compatible in all sorts of hardware (Raspberry Pi, Intel Edison, Beaglebone ... etc), I also had all sorts of fancy things (like level sensors , etape). But after doing all of that for good 8 months, I realized that very few of those things actually help me in better reef keeping. In fact it was clear that I can do reef keeping without a controller, but having one that does the monotonous work and adds some extra safety gears is actually worth my time and effort.
Now, all that being said, after reef-pi 3.0 release I think we'll nail down some of the advanced features as well (peristaltic pumps, wavemakers, clustering etc) and I am open for suggestion on moonshot ideas, but I would still emphasize on use case first. i.e. we have to think about what this particular thing gives us, just more of anything is not useful, but if we have a use case (for example, we may decide that we'll do time series analysis on the temperature /ph data and predictively alert folks when equipment or tank act anomolous, instead of fixed threshold based alerting) that actually benefits reef keeping , and the new fancy things is required for that, then I'll definitely consider it
I dont mean to be rude, but I want to keep reef-pi features (software and hardware) coherent, for it to be effective and for me to be able to maintain it easily. Hope you understand :)