no its wont work; The CPU's supported on the board do not support ECC and so the RAM chips wont initialize.
I asked the same question to support a long time ago because Server ECC memory was cheaper than getting non-ecc. Also it was available in 16GB DIMMS instead of 8GB; I was messing with the idea of 128GB of RAM.

Even the WS board doesnt support ECC; which was actually going to be my first choice since it has a PX Switch for PCIe and supports SLI with the PX chip (which is new);

Go look at the supported CPU and memory listings for Rampage V and X99 Deluxe.

They both show support for the same Xeon CPUs that support ECC memory as on the WS.
These CPUs also support non ECC memory.

They also both show support for Registered/ECC memory.

Personally I run a 5960X on my Rampage V with unbuffered 2400 DDR4 memory.

But on my son's X99-Deluxe I'm running a Haswell EP 8 Core Xeon E5-2667v3 and Registered/ECC memory without any issues. The ram initializes just fine. It's Samsung M393A1G40DB0-CPB which is on the lists.

Now whether or not the Rampage V and X99-Deluxe can actually utilize the ECC bits is a completely different question.
That may or may not be implemented, and I've never received a straight answer about it.
My gut tells me NO. So if you're looking for that, it has to be WS.

Don't take my word for it, look here at these two official Asus Support Docs:
http://support.asus.com/cpusupport/list.aspx?SLanguage=en&p=1&s=42&m=RAMPAGE V EXTREME&os=&hashedid=SNYTZvOdMa6xGWYL
http://support.asus.com/QVL.aspx?SLanguage=en&p=1&s=42&m=RAMPAGE V EXTREME&os=&hashedid=SNYTZvOdMa6xGWYL