I was thinking about upgrading to a newer chassis model, but I see the newer ones have moved to AMD processors that don’t support hardware transcoding.

If you’re open to suggestions, I’d suggest having your NAS doing what it’s best at, serving as file storage and then build an actual server that’ll be leaps and bounds better that’s directly hooked into it. As a file server, that NAS has many years of life left.

Looking at the price that NAS cost new, you could build an absolute juggernaut of a Plex server for around the same price.