Maybe you should consider selling spare discs, so the customer can choose their preference (I'll take Mk. 1 metal disc, please )
I'm serious, though, if they are swappable, it really might be the answer to your problem - just let the customer buy the DAP and then they could decide to attach whichever disc they prefer.
They could make them out of different colors while they're at it Would be such a hit with the fruit people Sounds like an idea? It really depends on how user-replaceable the wheels are though. I hope it doesn't involve taking off the front cover...
I looked at that early spec too but they assured me that the final spec X5 has more power than the X3. By how much I still don't know, but it's on the order of 30mW or so.