[olevelo]

Looking at buying a shield. I will be mainly watching UHD rips with HDR, Blu-ray rips and compressed 1080p files.

As far as I know, the only downsides are poor upscaling for non 4K HDR content and no Dolby vision. Is there anything else I should be aware of?

Also I’m thinking of using a hard drive attached locally to the Shield because I can’t run Ethernet. I’ve known some media boxes in the past to not be compatible with certain hard drives and certain hard drive sizes. Can the shield run essentially any hard drive through the USB ports?

As said above, the upscaling isn't as much of an issue because 1080p can output as 1080p.  However, 720p isn't supported yet (they said it will come soon), so it will be upscaled either to 1080p or 4k.  Also, DVD content at 480p will be upscaled to 1080p or 4k.  I think it's Kodi doing the upscaling though, not the Shield.

As for hard drives, I haven't seen any compatibility issues.  There are some with SD cards on the older version that still has the SD card slot, but if you're getting a current version then that's not an issue.  I have a WD 10TB from Best Buy that has been working great.