Remember that Thunderbolt (like FireWire) is bi-directional, which USB is not. The difference might not be noticeable if you're simply using the drive as a backup or are just transferring files. But if you use an external drive for video or audio production, as I do, the difference can be staggering.
So for encoding, it really might be worth it to score the cheaper TB1 version Rugged and replace the spinner with a good SDD like a 512 840 Pro. This topic is coming up more and more as we lose FW800 ports in favor of USB3 and TB2, aside from the wonky designed Seagate TB adapter, what is the best bus powered TB enclosure out there then?
It's really time third party vendors step up with plug and play solutions for SSD / TB users who want the small form factor, we are already at TB2 and it's like TB1 never even took off......
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USB speeds are burst, not sustained. USB devices are not daisy-chainable. many apple products do not have USB 3 ports.
Ok, well bring on the TB devices that actually use fast drives instead of a stupid 5,400 RPM drive then....or at least point us in the direction of where we can get them. Lacie? Maybe as even with the SSD's in there they are not going much above 400MB/s peak, it's a SATA-III interface, that is the limit. Buffalo TB drive? No, it also has a spinner and from what I gather getting the case apart is akin to outright breaking it.
Any other bright ideas because this sub 100MB/s spinner drive in a TB case crap is for the birds, just about useless....
I moved a 202GB folder of D800 raw files from my 240GB OWC Envoy Pro EX SSD drive to my new 13" retina with the 1TB PCIe last week and it never dropped below 500MB/s, moved the whole darn folder in under 6.5 minutes....this was via USB3. Also, it took me all of ten minutes to install a USB3 via PCIe card in my MacPro. It does not hit max theoretical but it is about 3x faster than FW800...
By the looks of it, the only way we are going to truly see TB speeds out of these enclosures is if the fast PCIe drives that Apple has put in the new MacBook Pros become available to 3rd party companies who can use them to avoid SATA-III and come up with fast plug and play solutions like OWC's Envoy cases do.