We have not yet tested on shipping machines, since no machines have shipped yet. However, on the Apple site, in the MacPro Performance area, you can see their test results with a pre-release Resolve V10, pre-release Mavericks on a pre-release MacPro.
As I tell everyone who calls, the performance is based on a mix of things. Storage bandwidth, CPU and GPU processing all play a part. Which one of those plays how much of a role depends on a multitude of things, like what type and resolution of source material, timeline resolution, sizing and grading operations performed, and render type and resolution.
Until systems of various configurations are out in the world, testing all these combinations, it's hard to give any precise guidance on exactly what type of system you should get.
As always, it's safest to get the best configured system you can afford.
I would recommend the 12 core, 64GB, 1TB flash storage, dual D700 system with the 32TB Pegasus Thunderbolt 2 storage, if you want to cover all your bases.

Sadly, not a system I can afford.