Frédéric - you´re completely correct about what I´m aiming to do.
Now, I have slimmed the installation down to 8x HD projectors, so we have the option on 2xDecklink UHD capture.
Then we could probably walk the path of the Datapath.
And build a nice, fat PC with a Radeon 7990 in it.
Thanx again, Frédéric, very solid feedback