I signed up for updates for this product and really thought it would never ship. Looks like Sonnet may yet prove me wrong...
Sonnet Products Update
Echo 15+ Thunderbolt 2 Dock Shipping Status
and New Products
Echo 15 Thunderbolt Dock Update
The Echo 15+ Thunderbolt 2 Dock has successfully completed the Thunderbolt Certification process and is now being manufactured. We expect to begin shipping against our very large backlog of pre-orders during the first half of September 2015.
The Echo 15+ has gained a few new features and an all-new enclosure design. As a result of Sonnet now providing support for installing two 2.5-inch drives in all models, all Echo dock models share the Echo 15+ name. This name change does not affect the model you ordered.
Take a look at the recently updated product page with more details on the shipping status countdown.
Sonnet Products Update
Echo 15+ Thunderbolt 2 Dock Shipping Status
and New Products
Echo 15 Thunderbolt Dock Update
The Echo 15+ Thunderbolt 2 Dock has successfully completed the Thunderbolt Certification process and is now being manufactured. We expect to begin shipping against our very large backlog of pre-orders during the first half of September 2015.
The Echo 15+ has gained a few new features and an all-new enclosure design. As a result of Sonnet now providing support for installing two 2.5-inch drives in all models, all Echo dock models share the Echo 15+ name. This name change does not affect the model you ordered.

Take a look at the recently updated product page with more details on the shipping status countdown.