If you decide to take the dive, I highly recommend the Zenith Extreme board - so much so I ordered a second one, to replace my only 1-month new Gigabyte board.
Why? UEFI has so much more polish, their ROG forum is excellent with UEFI devs replying regularly and even offer a beta (0801 right now) for download there).
On the Gigabyte front, I really haven’t seen much progress with their latest vF3g. Sure, IOMMU is enumerated across both Threadripper cores by default on the Gigabyte board, but groupings are pretty nasty.
Since I’m going 10G as well, the additional Aquantia card provided with the ZE is fine meaning the ZE mainboard’s actual cost is closer to $300, since most decent new Intel 10G (copper) cards are in the $200 range anyways; getting features like DIMM.2 (makes swapping out and accessing M.2 sticks SUUUUUPER easy) just pushes me over the edge in terms of convenience etc.
I also believe the Asus UEFI has better support for PCIe bifurcation (which the Gigabyte may be lacking on?) should you want to say run 4x M.2 NVMe in RAID off a single slot via the Asus Hyper M.2 card (only $60…wow)