I have an 8x4 foot machine, and it’s a big boy, old software I don’t like, steppers, i rarely use it... but I know ONE thing for sure, I would probably not recommend a wood frame. Our steel frame weighs a figurative ton (or metric literal, IDK) and it STILL is not stiff enough for large 3D contoured parts with tons of little steps.
I'm running a 5x10 which physically is 7'x12'6" with Nema 34's. No lost steps over the years, aside from crashes. It will snap a 1/4" bit without losing a step. It's on a steel frame that is 900+ lbs of steel with 3 sheets of 5x10 3/4" mdf and it still vibrates every now and then. Machine time to planning/cad work is probably 1:10 which is about in line with my development work - 10hrs design for each hour of programming.
Mostly utility stuff around the house. At one point, a custom chicken coop. My use case is unlike commercial/industrial. It serves as an 'infinite jig', a work bench and a platform for experimenting. I can see driving it with Klipper. Mach3/gcode is like batch mainframe work. Klipper/Python could make for a much more interactive experience. eg. vision for work piece alignment and then be able to say "give me a 1/2" dado down the back with system 32 shelf pins.
