Well I installed Yosemite Beta 3 on my Mac mini today. Already used the Feedback Assistant to report this... I've got a OWC Helios with a PCI eSATA controller installed. Never had an issue (even with Public Beta 1 and 2), as the driver for the eSATA card has always been included with OS X. Needless to say, the eSATA controller stopped working after the upgrade. What I'm wondering is whether this is an issue with the driver for the eSATA controller, or if there is an issue with Thunderbolt. Since I have no other Thunderbolt devices, I can't test it. Has anyone else had problems with Thunderbolt and Public Beta 3?