You'll need a MMU to control caching in case you have a DMA device in the system - if the Vampire has a cache (I believe so). For the A600 and no other extensions, this is probably harmless (IDE does only PIO, and there is no Zorro bus).
But without a MMU, you'll run into trouble as soon as you would try to run this in a big-box machine with a Zorro card that can run DMA. Reasons are a bit technical and due to the rather convoluted Amiga Bus system, but it's a major headache getting this right. It's usually the 68060 or 68040.library which takes care of these pecularities.
the obvious solution would be to to implement mmu, another possibility, less obvious would be to include all high bandwidth periferials like sata/pata, usb, lan and rtg onboard, with or without classic dma, but either way with an adequate firmware support to make zorro extensions obsolete. a low cpu load while data transfers beyond 10mb/s would be enough not to need zorro for anything much demanding anymore.
