Full release notes here: https://www.hauptwerk.com/download/8175/
Lots of improvements, but the highlights:
- Completely new audio engine, with a mixing solution that allows divisions and pipes positionable in 3D space, with multi-channel output to an insane degree (512 channels for the standalone version. 16 if using with VST/AU Link)
- Higher performance engine allowing greater polyphony.
- Built-in 4-channel convolution reverb.
- Improved realism due to higher resolution processing of the wind supply model, pipe flow turbulence, swell boxes, and tremulants.
- The Aladdin HASP protection system has been replaced with iLok, and can use either cloud or dongle licensing.
- New subscription model, but perpetual licensing is still available.
- Catalina support.