I built a 12-bay NAS recently. I snagged a 5900X/Supermicro server board/128GB DDR4 ECC combo for only $680 on eBay right before memory prices went apeshit. It has IPMI and 2x10g. Suffice to say I belive you can roll your own appliance like this for considerably less money, and have far more control over it. I say this as a Unifi fanboi.