Hi
I'd just thought that I'd post a tiny little feature suggestion, and that is if you ever do an update on the AF-4 (which sounds gorgeous btw) please consider adding an audio input as a modulation input for the filter cutoff freq.
The thing is that Reason only runs it's CV signals at a 64th of the audio rate so to be able to do proper audio rate FM of the filter we would need an audio jack input as a modulation. If you need any reference you could perhaps take a look at the back of the pulveriser device in Reason 6.
And if not for the AF-4, at least for your consideration if you are making other RE's where audio rate modulation between devices might be a desirable feature.
Cheers!