One thing the Audya does is that many of the audio drum parts were recorded with the same drum kit, in the same room. This makes disassembly and reassembly into other styles fairly coherent.
But most of what I've heard of the Yamaha audio styles sounds pretty different from style to style. Although you may be able to use them to put other styles together, unless you use the entire drum Part from one style for another, I think you may well have the odd effect of one Variation on one kit in one room, and other Variations having a totally different kit, in a different ambient space.
One more reason why I feel that drum KITS, not audio drums, is the way forward.
You are completely correct. This was one concern I noticed when I heard the Audio Styles on the PSR-S950. Must be the same issue on the Tyros 5 when I get to hear more the Audio Style demos.
I guess if the difference between the Audio Style part and the rest are that noticeable you could alway adjust the DSP effects to the other style parts to approximate the correct room environment. A lot more work, but possible.
Audio parts do add another dimension to the style and they have their place for certain song specific styles or style audio effects, but I also would prefer total midi control and just make the style and kit samples better quality or longer (eg.cymbals) as technology allows.