The free 4U 2.0 upgrade is nearing completion. Serious apologies!
Version 2.0 will add 8+8/16 channel polyphony, a 2d display for the envelopes, tons of CV connections, custom meter/display colors, many more controls, etc. See the new videos (the last 4) for a look at it and the KRON in action. The very last video is the most recent. Note though that it is now 4U, not 3U, adding user controls, a patch browser, even more options, etc.
The PSDN is a curved dual CV envelope generator with tons of options. The envelopes can be combined or used separately, one launching from the other, triggering additional PSDNs, etc. It's versatile! And it will be even more so when version 2.0 comes out.