After a couple of years running the original firmware, which supported both bands, I grew tired of such an ancient version (15.05 plus GL mods) and installed 18.06.2, which only supported the 2.4GHz band. Now this radio is acting up and I bought a Fritzbox to replace it.
Long story short, I have a mostly functioning MT750 that I could donate, ideally to one of the developers working on getting the 5GHz radio supported but also to core OpenWRT developers. I will pay for the shipping, of course.
Please show some proof of your involment in the project (git repos) if you're interested. If no one is interested, I'm simply going to keep it, as a spare switch or to reinstall the original firmware.