I prefer a TrueNAS box for this as a target for DR (disaster recovery) -- there's nothing as good as a ZFS send, especially compared to rsync. I don't really trust home routers with USB ports to have high availability or acceptable performance. I see it as an afterthought or "gee whiz" feature. Maybe the Apple TimeCapsule devices are more solid by design, but even Western Digital's MyCloud NAS left a LOT to be desired (performance, security, etc. were sorely lacking). I have several Netgear Nighthawks with USB3.0 ports, but I must confess I've never even tried out that feature. But I'm sure you could find anecdotal experiences online, as well was benchmarks.