So I bit the bullet and bought a couple of diskless My Cloud EX2 Ultras since I was unable to cancel my order of two 10TB WD Golds from Staple.
To my surprise the two 10TB drives do work on the EX2 Ultra giving me 20TB/10TB mirrored. The other surprise is that I do like the EX2 as it reminded me of my single bay my clouds. Apparently it seems to be running the same Busybox gen2 OS that everyone grew to love on these forums.
The speed of the NAS is very nice giving me on average a 100MB/s reads and writes.
I did try mounting one of the Raid 1 drives on a USB Thermaltake BlacX Duet Dock to see if my Mac could read it and of course it couldn’t; It wouldn’t mount. So that isn’t a good sign.
However, swapping the drives to another EX2 enclosure allowed me to integrate the drives without any problems, so that solves the problem of recovery if the enclosure dies.
I did do all the test of yanking out the drives (unit turned off) to see how it handles itself with a simulated drive error or rather no drive error 
and it was impressive. Reading and writing to one drive was exactly the same; no speed difference.
I added a few more files to disk 1 while disk 2 was removed and after inserting disk 2 back in and turned on auto-rebuild, the re-build process was very quick as it seems to only re-build the missing files.
I did re-format disk 2 after removing it and the re-build process automatically re-formats disk 2 when re-building. However for a full re-build of 10TB, the clock indicated a 12 hour process. Since this was a test, I reformatted the 2 drives. I don’t know if the re-build process is smart enough to just re-build the data on the second drive or will it re-build the whole disk a track at a time.
At the moment I started the copy process which will probably take me a week to copy all my data from my 8TB my clouds. I am about 90% sure that I will be keeping the EX2, mainly for the reason that it is like a big brother to my old 8TB my clouds and familiarity is important to me as I get older because I really hate doing all these tests.
The other thing to note is the fan never kicked in even with my first initial marathon of disk copying.
Lastly, my sleep script works perfectly on the EX2 since I believe it is the same BusyBox gen2 OS3. The EX2 slept within 5 minutes of inactivity.
It is a good NAS unit, just like my old My Cloud.
