If you want to boot from a Hammer 2 /boot volume, you now can.  Hammer 1 never worked well as /boot, though it was technically possible.  Hammer 2 will be just fine.

Note that you can’t turn on recently-added disk compression since the bootloader doesn’t understand it, and Hammer 2 is not ready for anything but being worked on.  Don’t try it unless you’re ready to be submitting code changes to fix Hammer2.