ASUS has done away with SATA express and U.2, glad they did
The Extreme has 2 M.2 slots one under the bottom of full block, water cooling for your M.2 drive, second is under the bottom of the PCH heatsink where Arne pointed out, the block looks fantastic if your building a daily use water cooled system, maybe the block will be optional, or maybe the standard VRM heatsinks are included, we should know pretty soon
I haven't used sli on my M8E and have never used the pcie lane switches except on the big platforms, X-58-79-99, wish they would add pcie switch for M.2 drives
The Apex is really a pro bencher board, so probably not necessary to have M.2 but it may on back of board, only 2 ddr4 slots for highest memory speeds and a single ddr3 when you tuned the memory to far and it won't boot flip a switch and boot to the ddr3, seems like an LN2 dream, maybe not my cup of tea but I am glad to see a board designed with extreme OC without the gaming extras attached
Would like to own either board myself but the Extreme model has always been my preferred board regardless of platform