So after checking the options, a while back I picked up a RE-ARM and a RAMPS 1.5 board which is on the lower end of the cost for 32 bit goodness. These two boards act like the brains and nervous system of a 3D printer. Along with running the software (either Smoothieware or Marlin 2.0), they also manage the power necessary for the stepper drivers, the heater bed and the extruder/s. The RAMPS is a draughtboard designed to manage stepper drivers and heater MOSFETS for an Arduino Mega originally, and it has unofficially evolved through several iterations to improve some things while completely ignoring others. I decided to pick up the latest iteration which is the 1.5 which I don't see too many people using, but appears to have better management of the MOSFET's cooling. One of the big considerations with any RAMPS board seems to be the connectors which are generally regarding with suspicion as being just barely spec'ed out for the currents needed on some printers. Mine should be OK however and I don't expect any issues. The other thing to look out for with RAMPS board (actually one of the other things, is poorly spec'ed components) like MOSFETs and capacitors. It is tough to check these since many Chinese boards may use questionable MOSFET's in the first place, and the caps may be hard or impossible to read, so it is just one of those things to be aware of. A nice alternative to RAMPS is the PICA which addresses the questionable build quality, suspect connectors and appears to me to be a well designed board. It is also 4x the price of a typical $10 RAMPS board. The PICA is also not out of the box compatible with the RE-ARM, but it is on my list once I get things running well enough. For now though I just want to get going with a 32 bit board since I am having all sorts of failed prints (and I want to do it anyway).
As for the Re-ARM itself, the major consideration is that it runs on 3.3V and is replacing an Arudino Mega which runs on 5V. This means that care needs to be taken with anything plugged into the Re-ARM or RAMPS board that may send a 5V signal though to the Re-ARM - which could blow out one of the Re-ARM's IO pins since they are not protected. Most things should be OK in my build since I use mechanical limit switches. The other concern I had with the Re-ARM which turned out to be unfounded, was that it would not be able to provide 5V to the MOSFET's on the RAMPS board - turns out they designed the Re-ARM with 3.3v to 5v level shifters for the outputs used for the MOSFETs so that is all good - these are only for the outputs however so the inputs still need to be connected with care so as not to give them more than 3.3V.
Last night I was able to first upgrade the stock Smoothieware on the Re-ARM board, but then decided to try installing Marlin 2.0 again. I'm not sure why I want to use Marlin, but it's what the cool kids are doing so I was happy to finally get that working. Unlike Smoothieware though, Marlin is not easy to get started with. Smoothieware just requires downloading a firmware.bin then you load that on a 32GB SD along with a config file and restart the Re-ARM, then you are in business. Now the config file is nothing to sneeze at though, it included all the pin definitions and settings that will be used (and is actually more complicated than Marlin's configuration for that reason).
Marlin on the other hand requires downloading Atom.io, then installing PlatformIO - from within Atom.io (which was nothing but problems - make sure to run it as administrator to solve a few of them). Once that is running I had to open up the unzipped Marlin 2.0 directory in Atom, finding the configuration.h, editing that for the type of board and other parameters being used for the printer - I used a sample config for a kossel and added my settings. Then compiling the whole mess into a firmware.bin which inconveniently is just saved in a subdirectory buried deep with the one being worked on (mine was inside "\Marlin2.0\Marlin-bugfix-2.0.x-6-22-2018\Marlin-bugfix-2.0.x\.pioenvs\LPC1768\firmware.bin" (so no option I found to save it anywhere else). Compiling also hit a few snags since I accidentally commented out a if statement and had to find it to fix one error. Another error ("Marlin\src\libs\buzzer.cpp:63:11: error: '::tone' has not been declared") was due to having set up the speaker up for my display board. Fixing that required disabling the speaker - on line 1629 in configuration.h - since it is not implemented yet for LPC1768 (Marlin 2.0 is still in development so this is something that will get fixed in time):
After a few hours, I was able to get a good Marlin2.0 firmware.h, and loaded it up on the Re-ARM without a problem. So next up is getting it all put together which should be easy but really it is not since there are some quirks of the Re-ARM such as requiring a special cable for the display (due to the Re-ARM running at 3.3v versus the 5V typical of the Arduino Mega it replaces). There are other considerations as well, but lets just say I am taking it slow, so I don't fry something.
In the mean time I am also working on a means to hold the Re-ARM + RAMPS 1.5 boards and have come up with a two part enclosure that will mount in the same location as the current board in the Anycubic Kossel Plus. It is not a perfect design, I may re-design the way the lid attaches with screws, sometime down the road, but for now this should get me started.
Models used from Thingiverse are: