If your only holdback on a Plex Server is the cost/impact of running a PC as a server full-time, you might want to consider the NVidia Shield. It's a capable Plex server (without the power draw of an always-on PC), client, plays your rips with full HD audio passthrough, and handles streaming extremely well. Its main drawback, lack of Dolby Vision, doesn't apply here since you're using a projector. The only other real drawback, in my view, is lack of Atmos support for Netflix... the ATV4K does this but, IMHO, the lack of HD audio passthrough outweighs the benefits. There's almost definitely a new Shield device coming soon, but I don't think it will offer anything materially that the current model does not.