Hey Rolf,

I think Mike already has one of these. I know for sure that he has an ATEM 4K Procuction Studio.

Might be worth asking him.
We had same bad expierence with the internal Decklink 4K Capture Card. But I never had a chance to try the TB-Version.
Will try to get a demo-machine from my dealer here in munich and let you knwo the results.

Best

Marc