Sorry to hear of your issues. I’ve contemplated the Quatro / Shield TV combo as well but just as much for others for future reference (not implying you don’t already know this, I’m sure you do), the key difference between the Quatro and Tablo is the hardware encoding the Tablo does so the recorded media is already in a format that can be played back on multiple devices (for me Roku, multiple Android devices, Shield TV) with no further transcoding required (Direct Play in Plex in fact).
Are you planning on using the Shield TV as the Plex Server as well or just for playback? Not as much of an issue if you are only going to be doing playback via the Shield TV (I have one) and the Plex Server is a separate, beefier machine. However, as a Plex Server the Shield TV can only really handle 2 simultaneous 1080P transcodes and with the Quatro recorded media needing to be transcoded for most playback devices you can run into a resource crunch quickly if you have multiple people trying to play back recorded content at the same time.
Of course, the HDHR Extend can be a solution to that issue since it does hardware transcoding just like the Tablo, but it’s also more expensive and is also only available with 2 tuners. Since I have a 4 tuner Tablo the cost to move to a comparable 4 tuner solution with HDHR tuners (2 Extends) has kept me away from researching that solution any further right now.