ferebee wrote:I did consider using an external PCIe chassis, though I wonder how much difference that would make, as the various Thunderbolt docks presumably do the same type of Thunderbolt-to-PCIe conversion internally.
I think it would make a big difference because the components are likely much higher quality in a PCIe chassis than in a consumer-oriented Thunderbolt dock. Also, I don't think the PCIe chassis + PCI express card will be subject to the same bugs as the Thunderbolt docks. The docks are not necessarily doing the same type of conversion internally. They are probably using some new fangled boards that convert from Thunderbolt to USB and then put all of the other dock connections onto the USB bus. The PCIe chassis is going to explicitly go through full-on PCIe, with the Thunderbolt specific parts of the board only having to do a Thunderbolt to PCIe mapping, which should be straightforward because Thunderbolt is PCIe. Then the well understood PCIe to PCI express card connection will be made, and at that point you're relying on the PCI express card to do the heavy lifting. The key will be whether the PCI express card can handle all of the sleep/wake issues, etc. well.
The Echo ExpressCard Thunderbolt Adapter Pro does look like a pretty good option, too. Note that it only has one Thunderbolt port, whereas the OWC Mercury Helios PCIe Expansion Chassis has two Thunderbolt ports, so that it doesn't have to be the last node on the daisy chain. Also, it looks like the Echo ExpressCard Thunderbolt Adapter Pro does NOT have its own power supply (uh oh), whereas the OWC Mercury Helios PCIe Expansion Chassis DOES have its own power supply.
Power can be a really big part of the Thunderbolt reliability puzzle. Check out this fascinating post to see what I'm thinking of in particular:
http://wolfgangtechnology.blogspot.com/ ... apter.html
ferebee wrote:Regarding the hypothetical $29 Thunderbolt-to-USB3 adapter - that should be a straightforward derivative of the TB-to-GigE and TB-to-FireWire800 adapters, don't you think?
No, I don't think it would be a straightforward derivative at all. 800Mbps for Firewire and 1000Mbps for Gigabit Ethernet are very different from 5000Mbps for USB 3.0, of which about 1000Mbps is involved in encoding alone. Also, Firewire is a direct memory mapping technology like PCIe and Thunderbolt, whereas USB is a completely different technology.