Hi Runedog,
speaking of the Audya, it's still on a preliminary phase and shouldn't be available for sale before next summer (there was a recent demonstration in Milan, Italy, and the guy who did the demo admitted that they have still work to do to make everything work as intended).
Speaking of the SD5, I think that it's a more modern keyboard compared with the SD1 and -even if the SD1 is still considered the admiral of the Ketron line- the SD5 has without doubt better sounds and fresher styles. The SD1 has the advantage of the 76 keys, the hard disk (which is optional on the SD5) and the sampler; the SD5, on the other hand, has a much better system of classifying and retrieving registrations and this makes it really easier to use.
Hope this helps you with your decision.
_________________________
Korg Kronos 61 and PA3X-Pro76, Roland G-70, BK7-m and Integra 7, Casio PX-5S, Fender Stratocaster with Fralin pickups, Fender Stratocaster with Kinman pickups, vintage Gibson SG standard.