After upgrading to the milestone 19 (m19) release, the new loader will be available but the system will still use the old Grub bootloader. This is chosen as a safe default because it's not easy to boot older Grub-based boot environments once you've enabled the new loader.
Therefore, you should only switch to using the new loader once you're fairly sure that you won't need to go back to an older boot environment.
Assuming your new BE is called m19, the steps to activate the new loader start with:
rm /etc/default/be beadm activate m19 rebootIf you still get Grub, then run:
bootadm install-bootloader -P rpoolIf you still get Grub, then run the following for each disk in the root pool:
installboot -F -m /boot/pmbr /boot/gptzfsboot /dev/rdsk/c0t0d0s0