Mesh Reduction, introduces non-manifold edges

[problemchild]

I'm building a complex model of the Eiffel Tower (Thingiverse thing:32825, file EiffelTower_Cut1_fixed.stl) using Creator ver 1.0.5. The file started as manifold, after reducing the mesh, ended with about 1/3 fewer triangles, but now have a model that has non-manifold edges. Is this progress? But I'm pressing on and printing it anyway. It has been printing all day, still going.

Can the mesh reduction cause degradation in details in the model? The surface is very irregular with lots of threads. (I'm new using PLA, so unsure what to expect.) Can something be adjusted in Creator to reduce the threads and the drool when the extruder is heading up. (Perhaps "exdrooler" would be a better term.) Retraction? Extrusion factor (now 95%). Temp (now 195 C).

[Simplify3D]

This is a known issue and a common challenge with pretty much any type of mesh reduction algorithm. It's extremely challenging to automatically repair these issues, but we're continuing to work on several post-reduction filters to help minimize the problem. That being said, we've used this method plenty of times and never really notice the non-manifold issues in the actual printed part. Many times they're just overlapping or orphaned triangles which don't cause major issues. The slicer is fairly robust and can typically cope with these abnormalities without skipping a beat.