It has Marlin 2.0.8.3-HW-V4.2.2-SW-V1.4.7G firmware which I am unable to flash over to other versions of Marlin for some reason, it just crashes.
My board is a 4.2.2. Obviously as indicated by the note above.
I don't mind changing the board out but I'm having a hard time finding any information on the 3 Max Neo and would rather not buy parts just to end up finding out that it's not going to work.
I would consider looking into Klipper. That would be a fantastic upgrade and there are plenty of videos on how to go about it. The documentation for the project is also easy to parse.
It was the first major upgrade I did to my Ender 3 that I got back in July. Way too spoiled by it at this point to go back to Marlin.
It all depends on what you're looking to improve in the printer.
Like already said klipper is probably the biggest upgrade possible but there are some other nice to haves:
Textured Pei sheet
Sillicone spacer instead of leveling springs
Bi metal heatbreak (increase safe max temp)
Capricorn PTFE tube for less drag in Bowden setup
I would eventually like to go to direct drive and potentially add another extruder at some point so I can print in multiple colors and print models that require supports using a different filament like PVA.
Basically looking to overhaul it and give it a bit more functionality.
I already have a raspberry pi with octoprint on it and a camera with remote access so I can check on it from time to time or send prints to it without the need to bother with the SD card.
I will definitely look into the things you mentioned also. I've got aftermarket springs on it already.
I swapped to direct drive myself. Went with the Creality Sprite Pro since I already had mounted a CR touch to my print head.I thought it made the most sense for interoperability.
On the old ender 3 you could put 90 degree brackets in the corner of the tower to stabilize it, which made big difference in reducing ringing, at least for the bottom 50mm or so.
But your version looks like you can't do that as they've widened the tower and stuck the uprights on the outside of the H frame. So I guess my advice is to find some way to stabilize the tower mechanically. Something like these angled rods maybe: