I casually associate with Michigan Tech's MOST lab & run their firmware, Franklin, on my delta very successfully. It does not require new electronics, and would work with the RAMPS board / arduino. The system runs in 32 bits on a debian system (beaglebone in most cases, but I've successfully compiled for Raspberry Pi and the trade offs vs beaglebone aren't a big deal). This could be a good way to run Gigabot, in fact, MOST has a gigabot and runs it on Franklin.
The advantages: TRUE, hyper-accurate mesh leveling (many many points with save-able bed mappings), 32 bit processing (arduino simply is a sort of pipe), can tweak everything - most in real time (I love adjusting the Z height by .1mm or so while the skirt is printing -- don't have to start over).
Disadvantages - not a big user base, functional interface (web server http based) -- not as pretty or friendly as octo-pi, and the big one, presumes that you know what you're doing (if you're in full admin mode -- there is a simplified can't tweak it user mode too).
I'll bring in my delta at some point and folks can play with it. I like Franklin, but I'm not sure others will take to it.
Lorin