though the surface offset component from pufferfish still can’t give me a single brep in some cases, I did manage to work around this. when setting up the different surfaces that the brep is composed of, I made sure that their normals all pint into the right direction. that way the SolidUnion component was able to join the breps to a single one after the pufferfish surface offset component. SolidUnion wasn’t able to do this when I had just flipped the surfaces before joining the together.
seem to me like carefully putting thegeometry together is always a good thing.
really a great plugin!
regarding the native grasshopper surface offset component:
I’m always a bit puzzled by the way the mcneel team treats bug reports. bugs that are probably painful to approach seem to get ignored completely. this kind of cherry picking reflects badly on the mcneel team, imo. the definition I uploaded in the start post looks simple to me and I assume teh behavior of the offset surface component qualifies as a bug - I still hope this will get addressed.
anyway, for now the work around does the trick for me.