Personally, I'd steer clear of Drobo. It pretends to be a backup in and of itself, but RAID isn't a true backup, and it's neigh on impossible to back up. Plus, it offers nothing that can't be done natively in Windows 8 or later with basic USB attached drives, which can be recovered easily if something goes wrong. If you want redundancy, Windows 8/8.1/10 can create it with any group of Firewire, SATA, SAS, USB, or pretty much any other kind of disk, just like Drobo does, without the Drobo expense, and with higher performance.
For me, I use a Windows Server with 4 TB Western Digital RE SAS drives with a hardware RAID 5 controller, and it recovers or rebuilds to add another drive in about 2-3 hours ... but that's overkill for most people ... then again, I use it also to serve up multiple DVD and Blu-Rays direct from the disks to my TVs, and can catalogue photos at the same time. Yes, I'm a geek.
Editing is pretty much out of the question over the network, even with my rig, unless you use iSCSI or Fibre Channel. You need block level access to photos, and SMB and similar only offer file-level access, so editing performance is terrible. What I do is edit on my local disk, then do a quick copy to the server.
You should also consider how you plan to back this all up. I use CrashPlan Pro unlimited, so it's constantly synced to the cloud, but in the Multi-TB realm you really do have to worry about this - do you end up picking up an 8 TB backup drive? Or the cloud? Or even tape?
