U-He today unleashed a new 'Researchware' plug-in named RePro-Alpha. It's a stripped down version of the Sequential Circuits Pro-One they're currently modeling.
RePro-Alpha by U-He
From U-He over at the KVR forum:
The research part is, we have implemented the same pretty extreme model of the CEM3320 Curtis filter chip in our vintage Pro-One using 5 different numerical methods, each costing a very different amount of CPU. We wish for you to spot the "most analogue" sounding method.
RePro-Alpha will be free forever, but won't be updated other than to the final commercial version.
Download here, spend some time with it, and don't forget to vote which filter behaves most analogue to your ears!