I am in a situation where I have two links through a provider that only assigns one IP address per MAC address via their DHCP. Because I do bonding, there is only a single MAC address on the bonding interface, and because of the lack of support for custom MAC addresses on per-VLAN basis, this has been causing problems, unless I use physical interfaces for each link.
I think there should be support for custom MAC addresses on per-VLAN basis in interface configuration modes. If someone can suggest a workaround at the moment, please do :)
A similar situation has also been described on EdgeOS back in 2014: https://community.ubnt.com/t5/EdgeMAX/EdgeMAX-VLAN-MAC-Change/td-p/485755