Here to say that this is simply the best streaming experience that I had - and I've used steam link (the hardware), Steam Link (app) on a Samsung Q70R, Nvidia Shield Portable, Nvidia Shield tablet, and the Nvidia Shield thingy that goes on the TV (both old and new versions).
Currently the stream is taking ~0.8ms to arrive, and <10ms to display @10mbps - 720p. I don't believe you need more than that (I'm rendering at 1080p and letting it be downscaled to 720p - this way it works as a 4x supersampling). Never had latency so low in any of my devices (maybe because I never tried something at just 720p?).
In switch the display time end up being a 1 frame lag, and I'm able to play platformers and quick reaction games (like Binding of Isaac) with no issues. All other games that don't depend on absolute 60fps frame precision will work perfectly, and the rest you can adjust your reactions to deal with one single frame (just like I got a platinum on jack and daxter on ps vita, running something like 15fps lol). Pretty nice to be able to play Persona 4 and 5 on the couch, or something like Fall Guys, or the other 1000 games that aren't on Switch.
To benchmark, I've also streamed to my phone (SoC snapdragon 855) and the switch version is better (no audio issues) albeit the display time is the same (~10ms). Directly to the TV (Samsung Q70R, using the steamlink app) it takes~ 1ms to arrive + ~19ms to display @30mbps - 1080p, sucks that there's no moonlight port to Samsung TVs...
All of the above tested on a 5ghz Archer C8 router, PC hooked to the router with Ethernet cable. On my experiments I noticed that enabling NAT Boost is strictly necessary to avoid transmission lag spikes (they are rare, but with NAT Boost they simply don't happen), so make sure any issue you have is not on transmission side (on all devices I have <1ms ping, absolutely stable).
I also disable QoS, firewall, logging, packet analysis, and every single thing that eats router CPU cycles or make packets be stored before being sent (for many of these functions, specially packet analysis and QoS, the router has to retain the packets in memory for a while, this causes lag even on a perfect 5ghz connection).
In my experience with streaming I'll say that unless you are maxing your CPU/GPU on a game (and you shouldn't at 720p) the specs doesn't matter on the final result (it depends solely on the client, unless you are running a PC from 10 years ago without dedicated GPU).
I would say that - if I didn't already have a Switch - this would be the "killer app" for me.