@matteo-nunziati I don't follow what you mean for "do you can afford for offline?" and I don't know what "NBD for backup" means.
@scottalanmiller I contacted xByte directly and the guy I spoke with (Ernesto) said he wouldn't recommend refurb (an R510) because "the hardware is 6-9 years old" (I guess I shouldn't be surprised by his comment...).
I'll definitely look into the R520 - thanks for the tip Scott!
The default onboard NIC on the R520 is a "Broadcom 5720 Quad Port Gigabit Ethernet". Should I just roll with that, or should I consider upgrading that? The options to choose from are "PCIe Riser Full Height" and "PCIe Riser Half Height". I'm not sure which one I would choose :-x... (other than the "full height" and go with the "Intel Ethernet I350 QP 1Gb Server Adapter").