Frankly it looks good to me and I see the seatstays as more of a style pick.
With Tour magazine style testing with a lower body only dummy they might have a negative aero impact, but IRL with you pedaling constantly and the dirty airflow around your legs the impact should be minimal. It's a bit similar with aero seatposts, IRL less important than people think (they still have an impact) and the added comfort of a round seatpost is something that most people should value higher.

Interesting. So Trek Madone should be less aero then competitors, too?
Is there an aero test proofing that?
The Tideace frame looks pretty thick from front view, this should be an disadvantage?
My biggest concern is that there aren't any reviews on this frame concerning safety/durabillity even after being some months on the market...don't want to be the first finding his teeth on tarmac...