Jens is smart enough to realise you don't need to mess around with attaching a totally unsuitable ARM SBC to an Amiga to get stuff you could get with an SPI master on the Amiga and some of the shelf parts.
I'm surprised that while you guys think up these "OMG you know what would be really cool" ideas you don't think outside of the box enough to realise that an ARM SoC many times more power than the fastest m68k Amiga could just emulate the whole thing.