Hi Michael, I can highly recommend the c-beam XL. On my build I have increased the Z travel by 100mm because I found the normal to be too constricting for my projects, and I have not noticed any loss of rigidity.
Having to file the beams square and to size is something I cringe at; filing things square and flat finished for me as an engineering apprentice in the 1960's; but it's a great skill if you have it!

We are fortunate in the UK to have an OpenBuilds kit supplier, Ooznest who cut the beams square and any length to +-0.2mm, drill and tap the ends.

Anyway, good luck with your build.