Thanks for all the answers :)
The only thing I need is T-Splines for complex shapes that I don't know how to make in MoI 3D beside building tons of construction curves
So the workflow is doing some parts in T-Splines and then boolean them together using MoI 3D

Also Michael, we need something like Auxpecker for MoI 3D :)
Its so awesome to work with and so usefull to get more visual feedback

Too bad T-Splines is not a standalone software :(