Wrap Up: Another Win for Synology
Between its solid performance, expandable storage support and reasonable price, Synology's DiskStation DS1515 is the perfect small/medium business NAS server. Granted, a reasonable price doesn't necessarily mean cheap, but at $650 the DS1515 has a lot to offer.
In comparison, the DS415+ is one of the best four-bay NAS devices available, but at $580 it isn't much more affordable, it can only use the DX513 as external storage rather than as an expansion unit, and only supports four drives out of the box.
Then the DS1515+ costs $770. It packs an Intel Atom C2538 SoC but there shouldn't be much difference between the DS1515 and the DS1515+ in terms of performance. Besides two extra USB 3.0 ports and support for the Docker app, the DS1515+ doesn't offer much for ~20% more money.
Compared to the QNAP TS-651, the DS1515 is priced close to the 4GB model and from what we observed Synology's offering is consistently faster on top of using slightly less power. The TS-651 also doesn't afford the luxury of expansion down the track and doesn't offer quad Gigabit LAN for advanced Link Aggregation and Failover support.
Our only real issue with the DS1515 is the lack of upgradable memory. Perhaps 2GB is sufficient for most, but it would be nice to know the option to upgrade existed if need be.
Where the DS1515 really shines, and this is true for all Synology products, is the company's DSM software. Every aspect of Synology's software is first rate, from the Web Assistant to the DSM 5.2 itself. Synology has refined its software to the point where setting up a DiskStation is extremely easy and anyone with basic computer knowledge should have no trouble configuring and maintaining the DS1515.
The build quality of the NAS itself is also excellent and the DS1515's understated styling looks professional. The tool-free drive bays are a nice touch and it makes installing new drive(s) quick and easy.
Opting for the Alpine AL-314 SoC in replacement of the more common Intel or Marvell chips is a bold move by Synology that seems to be paying off. The Alpine AL-514 in the DS2015xs proved to be one of the best SoCs for the job and the DS1515's AL-314 delivered the same amazing performance.
Pros: The DiskStation DS1515 delivers DS2015xs-like performance for a portion of the price. It's faster and more efficient while providing better expandability and network features than QNAP's TS-651.
Cons: Synology could have been more flexible with the DS1515's memory options and we don't think the DS1515+ should cost nearly 20% more for two extra USB 3.0 ports and the company's Docker app.