Folks reading this thread for hardware advice might also want to check this thread on a similar discussion and viewpoints:
https://forum.blackmagicdesign.com/viewtopic.php?f=21&t=55270Clearly there is a strong need for current guidance on Resolve hardware that is fact based on quality benchmarking.
As noted in the other thread and here, it is crucial to first determine your typical codec source material, resolution (1080p - 6k), and project length (30 sec spot commercial or 2 hr feature length). This info then guides you how to spend your budget money.
The biggest problem you'll run into in making an informed decision is the lack of sound Resolve benchmark testing of current hardware. The one video supplied in both threads demonstrating the dual Xeon vs single i7 was not as useful as it could have been because the wrong 4 core i7 was used and crippled with 67% less ram. But this benchmark video did show that even a far less expensive low end i7 4 core with far less ram was roughly equal to a far more expensive dual Xeon rig on short projects and 1080p material. Left unanswered factually was the hardware needed for long projects with high resolution material - so we're generally left with the assumption that dual Xeons are needed for long, high res projects still.
There is some good sound benchmarking of high end dual Xeon vs high end i7 hardware fitted with equal other components on a current version of Premiere which also relies on GPU power (especially nVidia Cuda). But it is still not testing of hardware on Resolve which could be written to use of more than the i7 6950 10 cores.
The question seems to be a need for an answer - does Resolve perform better with the far higher core count but lower CPU frequency of a dual Xeon; or does it function faster from the higher CPU frequency but lower 10 core limit of the i7 6950. Not an easy question to answer when you then throw in the mix of resolutions, project length, codecs, other software needed to run on the machine, and the cost of running these benchmarks.