For single home use, high performance HDDs are also unnecessary for a few reasons.
[list=1]
[*]SSDs are far better performers and the capacity/price has become fairly affordable; 120 GB should satisfy most users.
[*]Even if you do not want to buy an SSD for some reason, the average performance HDDs of today are still plenty fast.
[*]You are likely to be bottlenecked at 1 Gbps Ethernet (125 MB/s), USB 2.0 (30MB/s), 100 Mbps Ethernet (12.5 MB/s), 5 Mbps Unifi (0.625 MB/s) and so on.
[*]With multiple internal HDDs or external USB 3.0 HDDs that have similar performance, you could transfer at full speed but you will rarely do it nor need that kind of performance.