I used the Simple Sweep option in the Sweep1 command a lot in Rhino 5 and this seems to have disappeared in Rhino 6. The option makes a swept polysurface as solid as you would get when created by extrude combined with revolve. A radius on construction curves remains also a radius on the edges. My experience is that eventual fillets added in a later stage do not give any trouble. Without this option it sometime does.
I have looked at other posts referring to the Simple Sweep option but could not generate the same simple construction as I could in v5. The option does not appear at all, even when all is perfectly constructed. I copied the curved from v6 to v5 and there it worked out fine.
Best regards, Erik.