other than that, synapse-media-proxy seems to work well, nice and stable and memory use is pretty great too, even with all the thumbnailing.
Turns out most of the requests are thumbnails of media from other servers, which makes sense because that's how they appear in the timeline, only hitting /download when you click to see full res
except that my server discovery code *did* have a bug in certain server configurations so failed to fetch media from those... should be an easy fix today, and due to the drop-in nature it was incredibly easy to temporarily disable the media proxy
fixed and deployed :)