Relatively new to the market is the $360ish Gigabyte X-99-SOC Champion, expensive compared to previous Intel boards but a decent price for an X99 board.  It has four PCIe 16x slots of which two can only run at 8x maximum as well as three PCIe 1x slots, a single M.2 and a single SEx connector as well as a half dozen SATA 6Gbps ports which can run in RAID and another 4 which are only able to run in AHCI mode.  There are no C-type connectors but there are a plethora of USB 3.0 and 2.0 ports as well as a Thunderbolt header.  This is definitely a board for power users and manual overclockers as you can see in Hardware Canucks review here. 

You can also expect to see Morry's review of this Gigabyte board in the very near future.

"GIGABYTE's X99-SOC Champion seems to have everything it takes to become a legendary motherboard. It has high end overclocking built into its bones and a low price but will that lead to success?"

Here are some more Motherboard articles from around the web:

Motherboards