If working with USB3 is crucial to your situation, then you're probably working under Windows. I guess that rules out the Kona for you.
Regarding which is better for up conversion SD to HD, BM ultra studio Pro, or Kona, I guess that can be truthfully answered only by someone who has both, has actually done a play out of SD as upconverted HD out of both into another system that captures uncompressed HD, and then done a side by side wipe comparison between the two.
I've not come across any such test between exactly these two devices.
But I happen to have access to both BM as well as Kona cards. And I've run a test of the same picture from both into a Smoke, and then done a wipe test between the two watching the image on a Sony BVM monitor.
Honestly, not one of the assembled collection of finishing artists could tell them apart.
Sure, this is an empirical test, and maybe with some measuring instruments someone could find differences and even defects present in one and absent in the other. But to the discerning naked eye, none.
FCP Editor, Edit systems consultant