I was wondering when you guys were going to ask about that! :)
Audio In wasn't quite ready to go live when we launched, but I have experimented with it. It is definitely an interesting thing to slice up your own audio, but I found that Waverazor has specific properties that should be kept in mind to get the best results. When you're slicing at audio rate, it's the interaction between the slicer and wave frequencies that creates the additional harmonics (or inharmonics) of "Mutant AM". So if you feed waves from other synths or pitched source material, like singing, you will still be able to get that crazy ring mod-like response.
External audio that is not pitched doesn't have the same reaction. When you use noise based source material, it sounds like it's just being mixed in. (That's what you hear when you're slicing at audio rates.) If you're slicing at BPM rates, then it becomes a part of your wavesequence as a noise burst, or a gated burst of whatever it is you're feeding in there.
Another tradeoff is the loss of the ultra tight control over phase that Waverazor has over its internal sources. An external source behaves like a freerunning oscillator, where you never really know what phase you will catch it in when you launch a note. Among other things, that means you cannot apply Multi-Sync to it because you can't reset the phase of the external source (at least not currently).
Still, Audio Input is going to be quite a powerful feature. A lot of people asked how to get their own audio into the oscillator at NAMM, so it's pretty high on our list of things to do. Add to that the fact that we don't treat our user interface real estate lightly (i.e. we always want to pack as much fun and utility into the GUI as possible), and you'll be seeing the Audio Input come to life sooner rather than later.
Thanks for bringing this up and giving me an opportunity to talk about it!
All the best,
Taiho