Pure bi-directional fiber or hybrid fiber/copper (which all the cheaper ones are)?
I have a low quality 25' hybrid "Ablain" I use personally, just fine for Dolby Vision 4k, but I recently realized it's completely unstable for eARC in the reverse path and will need to be replaced.
I have a mid-quality 50' hybrid "RUIPRO" I use with a 4K projector, and it's been absolutely fine for that... but the projector doesn't even support ARC so I have no idea how good the return path is.
