Hello Eric,
if you have to capture 2 streams only, in my opinion is better to get 2 Decklink SDI cards; the Decklink Duo lacks of the Serial Ports that can always be useful. If you need 4 or more inputs, or if you need 2 inputs and 2 outputs, it could be better to get 2 x Duo or 1xQuad (The Decklinks are not Full-Duplex).
Ciao Gregorio,
I suggest you to not to buy a branded PC if you’re buying it for the Ultrascope or other BlackMagic products. It is easy to build (or to buy) a right PC almost everywhere. I suppose you to live in Italy, if you’d need some help feel free to write to me, maybe we could live in the same city :-).
Best Regards,
Have you tried to drop out the Decklink output and using another (standard not Blackmagic) preset for VGA preview only? Does Premiere still drop frames?