Beyond 8 bits per pixel, planar doesn't really make sense. Minimig-AGA on the MiST, FPGA Replay etc. work fine, excellent in fact. Just the other day I transferred a huge number of AGA WHDLoad games to my MiST and they all ran without issues. So I would say regular 8 bpp AGA has already been "cloned" successfully. 8 bpp planar is really all that's required for backwards compatibility with everything written for AGA. At 16-bit or 24-bit, chunky pixels make a lot more sense, and since nothing was written for 24-bit with bitplanes, it makes more sense to just use RTG modes with chunky pixels instead of trying to "emulate" something that never existed in the first place.
