Thank you Steve!
Would be great if you guys from McNeel can get in contact with Serif about that issue.
There are ways to get the geometry into Affinity Designer (pdf, svg) and the geometry is fine. But the real problem is the super messed up layer/group structure. So we need a way of getting our layouts into Affinity Designer by preserving the layer structure we had in Rhino. Otherwise AD groups the stuff randomly in groups and undergroups and this is so horrible you can barely work.
I hope by talking to each other you could both make some people happier 