I’ve built a couple machines with the V-Slot Linear Rails & C-Beam’s. They work really well. For now max length I’d recommend for the C-Beam is the 1M /w the ACME lead screw. Anything bigger is going to cause screw whip at high feed rates. With the C-Beam 1.5M you’ll have to use belts or get creative. I am currently working on a solution for the longer C-Beams, but that’s not something that’s going to out for a couple months.
As for positioning and use case for the XC/SO2 using C-Beams. I’ll more to share in a couple weeks.