First of all this made me experiment with 2 SATA controllers (which seems to work if I use chipset ICH9 (under System).GUI: VM storage settings page was adjusted a bit in usability regard. User is now allowed to change controller bus type and can move attachments between the controllers by using drag and drop
Host OS: Solaris 11.4
Guest OS : Solaris 11.4 - 2 SATA controllers attached to the guest
I can indeed drag and drop disks now between these virtual controllers and this seems to work.
Nice feature ...