One thing that is generally good about ACPI (well in some sense) is that it is free of callbacks, which I often hear as a disadvantage of Open Firmware's interface. (While dropping callbacks in OF is just a matter of directly providing the FCode drivers to the OS and let a hosted Open Source OF implementation use it there)
What would be neat is to decompile an ACPI table from binary, and ship that in the linuxbios image. THen you get most flexibility.
FWIW, this shows how to move your ACPI's DSDT table from bios to linux kernel, perhaps potentially elimitnating need for it in linuxbios altogether.