I'm comparing a WD and LaCie hard drive (4TB), looking to get the best performance per dollar spent. The LaCie drive has Thunderbolt2 and USB 3.0 connectivity, runs its disks at 7200 rpm, and can transfer data up to 180MB/s. Given that TB and USB 3.0 have max throughputs of ~20 & 5 GB/s, it seems there is no advantage to using TB with this device. Today I transferred a 73GB file from a macbook pro (SSD) to an iMac (SSD) via Thunderbolt Bridge over about 30 minutes. This is less than a quarter of the maximum rate provided by LaCie (HDD) - is there some other limitation on the transfer speed inherent to my system? The WD doesn't give any specifics (data transfer is "blazing fast"), but I'll assume it's the same as the LaCie. The only reason I'm considering the LaCie is because I already have one. I didn't do comparisons before. I needed an external drive, they had one at the Apple store, done. This time, the difference in price is something like $300, and I need to know that it's for more than just the "designed by _____" on the side of the box. Can anyone clear up the details about the specs and performance? Specifically, is TB superiors to USB 3.0 on one of these drives (i.e. is it worth paying more for the capability). Thanks.