Would you mind sharing your overall experience with synology? I'm planning on purchasing one for my home and all the reviews are positive, but I'm always eager to hear the bad side.
You may need to jump through some hoops to get the GPL code, but their product is (or was? it has been a while since I last played with their source code) reasonably open and full-featured, and works nicely out of the box. They also release frequent updates, have a decent set of options for backup / logging / media sharing out of the box, alerts are effective, and you also have an appstore-like for 3P apps.
Also, they use Linux as the base, and in some models you can even get access to the serial console with some effort, so you're not totally locked in on a proprietary system, should something go really bad [3][4].
I have a RS815+ and an old DS212+, and both are very reliable. Not terribly fast, but wouldn't expect much more from spinning disks anyway.
[1] https://wrgms.com/reverse-engineering-synology-openssh/
[2] https://wrgms.com/synologys-secret-telnet-password/
[3] https://wrgms.com/recovering-a-failed-synology-diskstation-d...
[4] https://wrgms.com/entering-single-user-mode-on-a-synology/