Last week I picked up a Synology 412+ and compared to my earlier NAS boxes (a D-Link 323 from several years ago and an Iomega/EMS PX300d) -- well, there's no comparison.
The UI is great. It's very fast. Management is easy.
The old D-Link is just old, early design, and so on. Nothing against it, really.
But the PX300d is a lot newer, and got good reviews a couple of years ago. And yet it never really liked being on a Mac network (I'm assuming I didn't misconfigure it). MS Office, for example, would sometimes be willing to save to it, sometimes not (all other apps behaved properly). Sometimes it appeared in Finder but wouldn't open up, or would open to the volume I wanted, but wouldn't show any contents. Basically it was a PITA.
And firmware updates? I learned not to do them, because they effectively wreck the box. After I had the Synology running properly, and had moved everything over, I updated the PX300d and, no surprise, my group and users disappeared and (this was a surprise) admin was locked out of creating new users.
I should have bought Synology in the first place. OP, if you buy a Synology box and connect it via gigabit ethernet, you'll likely be a happy camper. If you have to get an inexpensive gigabit switch or a different router to make it happen, do it anyway. It'll be worth it.