u-he has announced the availability of their latest "researchware" plug-in, RePro-alpha. It's the first step in u-he's recreation of the classic Sequential Circuits Pro-One monophonic synthesizer.
This free alpha version is a way for u-he to gather feedback on various filter models which will help them decide on the best implementation for the final version.
Download RePro-alpha, play with it, try the different filter models stuff, build an opinion, and then vote in this thread in the KVR forum. Take your time and think about what differences you hear in the filter models and under what settings do hear the differences.
The alpha version of Repro is available for Mac OS X (AU/VST/VST3) and Windows (VST2/VST3).