Synology are quite good, in my experience. They do require some more work to configure all drives, but that should not be a problem for you. Also, they have a nice and quite advanced web based GUI.

I used both a Drobo FS (1GBbps) and a S attached via SATA, and while the FS was not bad, I would recommend the S via SATA in terms of performances. They both seemed a nicely built devices. Because they were part of a project that we concluded, I haven't been using them for months. I used them for 6 months, only, in any case, so while I was happy with them, I can't speak about their reliability.
Oh, the FS was upgraded from a 3x2TB configuration to a 4x2TB (added 1 HDD) without any issue.