This has the big limitation, at least at the moment, that the supported providers all cap out at 1 TB for any kind of reasonably-priced storage.
> edit: be warned that many people are receiving 24 hour bans utilizing their Google Drive as network attached storage with Plex.
With that said, using the Shield as the server greatly improved our previous streaming situation. Before using the Shield, we'd struggle to maintain two good quality streams at once, whether both were local or one was local and one remote. The previous server was no slouch: Core2 Quad with 8GB of DDR3 RAM, but it seems the Shield is well qualified to handle server duties.
The other concern the Shield mitigates is power inefficiency; that C2Q is a power hungry beast, and the entire Shield box uses less wattage at full load than the Intel CPU alone at idle.
Those cloud providers likely don't want to get into the business of hosting media files that go into Plex. There aren't a lot of legal ways to get TV shows and movies (the bulk of the space) into the DRM-free format that Plex needs.