The issue isn’t going to be recording speed of the nas - lots of people running
blue iris and recording to both external drives & NAS. You don’t need thunderbolt or even usb 3.1 speeds for that.
The (theoretical) issue is the “t” series processor they put in the micro/tiny form factor pc’s. To get ultra-low power consumption, the “t” series processors run at a lower clock speed than a non “t” processor & also throttle themselves when they get warm ... so, theoretically at least, an 8700t is more likely to choke when you load it down fully with cams for a sustained period of time.
I don’t think anyone knows (yet) if there’s enough processor there at the lower clock speed to run the kind of data through one that you expect an i7 to run. Pretty obvious they’ll run a few cameras - just no one really knows at this point how many cameras “a few is”.
I’m personally in love with the tiny/micro form-factor EliteDesks & ProDesks.. I bought an i5-8500t micro/tiny form factor & a toshiba survellance drive to mount externally & tinker with via blue iris, but I haven’t got a gaggle of cameras online yet to torture-test it with. A couple cheap cams at max bitrate doesn’t seem to fluster it so far- not sure where it’s gonna hit a wall.. I think there’s definitely a use-case for tiny blue iris pc’s stashed in places a burglar would never look or that would not be easily accessible in the average time a burglar spends in your home. The micro form factors usually include gigabit lan, wireless lan, Bluetooth & hdmi - so configurations where the micro is literally physically inaccessible to the owner are possible - it can output to a tv & be updated via the wireless lan and controlled with a Bluetooth keyboard and mouse.
Bottom line, the SFF is cheap, reliable & a known quantity - and it doesn’t have the “t” processor. You can go back to the 6700 (non “t”) processors in SFF form & run a dozen cams recording to two 3.5” drives in one box, with no gymnastics- and the box can be had on eBay for $250 or less, or more - if you want/need a 7700 or 8700.. if you’re spending someone else’s money, probably a safer bet to go with the known quantity.
A side benefit of the older / cheaper hardware is that it’s so godawful homely that I’m guessing your average meth-addicted burglar is going to know that the pawn shop won’t even buy it for $10.