I'm feeling irritated after wasting $25 worth of high end filament on a bad part and reverting back to Cura to get a good print. I've been here before - attempt several times to adjust settings, preview looks OK, send the print, get a poor outcome, and go back to plain old Cura. Simplify 3D has great features, but the basic truth is that it's missing critical functionality. Namely, variable outline/fill thickness. Thin walls are hollow. Concentric fill leaves a void in the center. Some small parts actually fall into two pieces because the software refuses to fill the interior. Cura never makes these mistakes, and produces parts that are dimensionally and structurally awesome. Too bad it lacks advanced features.
One partial remedy involves lying to the software about my nozzle diameter, or specifying a narrow manual extrusion width. That's silly, unintuitive, and only works as a band-aid that can be used to tweak a specific part into working. Increasing fill overlap percentage introduces new problems.
If anyone has a reasonable, consistent answer to this problem, I'm anxious to hear it. Mostly I'm venting, and hoping my investment in this software eventually ends up giving me satisfactory results.