Basically the Synology spanks the FS up and down the street.
Features: To a first order approximation FS has none compared to the Syn. On the FS it takes the hard work of our good Ricardo, and self determination to install for extended software. You can find the list of Syn features on the web, and as it’s x86 installing ones that don’t come default looks vanilla (already found a page on installing Git)
Performance: I’m not into measuring (despite being a measurement scientist by day!) but I’m doing a time machine backup right now to the Syn and it’s kicking the butt of the FS by a huge margin (caveat - I am using faster drives in the Syn but this performance far exceeds the FS.) Eyeballing it I’m seeing (very roughly) a GB/minute. The other wonderful performance boost is mounting time. My computers are put to sleep and waked all the time, and the stupid FS takes forever to mount again (20 seconds?). The Syn mounts in a second or two - heaven!
Other: Quiet. I’m a noise freak, and I had to put the FS in a closet. The Syn is quiet enough to be in the same room. Not silent, but pretty darn good.
Supports open source filesystems. You can specify standard Linux RAID if you want to save your data in the event of a system crash.
UPS support (I’ve got it managing the UPS and broadcasting shutdown events).
Expandable (I tried a SansDigital eSATA tower I have but it wasn’t recognized unfortunately) with external bays
USB support (I have spare external USB disks attached)
What does FS do better? Fit and finish. The Drobo is way more solid of a device, oh well. I’ll be keeping the Drobo for weekly backups from the Syn I suppose.