RedJaron
Splendid
Shneiky :
I would buy such a board. If I have to chose between having more phases on the power design, better caps or a nicer power delivery, thicker PCB or aesthetics or any of those over USB 3.1 - I would definitely drop USB 3.1.
Absolutely. An aftermarket card with 3.1 can be added down the road if you really need it. Upgrading your VRM, card slot layout, or PCB strength requires a whole new board.
Ideally, yes, you find a board that has all the new features you want. But if you can't find everything, strat dropping the features that are easiest to address with third-party add-ons.