Hi,
I have the Asrock N3150dc, 4GB, 2 x HD WD 6TD red, 1 x HD 4T red, Raid 5, DSM 5.2-5644 Update 5.
Before the update, but I do not remember the previous revison I had (anyway 5.2-xxxx), everything was working properly. Now the USB3.0 always disconnect any external hard drive (it does not matter if it is supplied by the USB or by external power supply) as soon as I try to copy anything (sometimes it lasts for 1-2GB). This is a software issue and not a hardware related issue (I have also upgraded the power supply from 60 to 90W). The USB2.0 always works fine.
With regards to performance, as a NAS is stunning, as Plex machine:
1 x stream of 12GB MKV - cpu 30%
2 x stream of 8-12GB MKV - cpu 60-65%
3 x stream of 8-12GB MKV - cpu 95%, sometime video stream stops.
BUT
1 x AVI 300MB - CPU 80-90% - no issues with frames
more than 1 AVI - randomly freezes
If you do not use PLEX but you use your computer / IPAD / iphone / Android phone to play directly the MKV or AVI files, 3 MKV + 2 AVI - CPU 15-20% only (obviously you are not using the N3150 processor to transcode).
Bottom line, the N3150 is a very good choice, but, if you do not need the DC version and you intend to use a standard power supply (100-150W maximum will be more than adequate), I would go for the N3700. The passmark is just better 1913 vs 1680.
Please note that there are two new versions of the processor: J3160 and J3710.