I'm totally with you on this.
Although it could be done for home use, when they asked me to experiment with it at work in summer last year I said: absolutely no!
The reason is exactly what you highlighted above, I said "there's no way I'll ever certify something like this" mostly 'cause I'm pretty damn sure that even if I used real-time filters in Avisynth getting the incoming stream from the sat decoders from our MCR via SDI:
1) It could crash at any moment
2) There's no way it would be able to sustain days of workload without rebooting etc
And of course one could make all the arguments of the case like putting a DFS in front of it and using AJA cards instead of Blackmagic decklinks for input/output, but the benefit vs risk still wouldn't cut it.
I mean, I would rather have no filtering and a crappy hardware downscale with gibbs ringing and what not than to have perfect quality until Avisynth crashes in the middle of a game and it takes forever to bring the frameserver back up, people at home complain (and I'm blamed for it).
By the way, it's funny how we tested the same things 'cause I made the same tests myself and with the very same technology
(and with pretty much the same results...
)