Earlier had noticed that a first layer height of 150% would add 0.1mm to the height of the part. Assumed that Simplify3d was nonetheless doing its best to get as close to the part height with an integral number of layers (and that no adaptive layer heights had ever been implemented - that would be good!).
Just did some tests and the situation is actually much worse and so am filing a bug report.
If layer height is 0.2mm and 1st layer height set to 150% then the part height will increase by 0.1mm
If layer height is 0.2mm and 1st layer height is set to 200% then the part height will increase by 0.2mm. WHEREAS it could have been made precisely correct by reducing the number of subsequent layers by 1.
This pattern continues as first layer height is increased further. The the first layer height is therefore not taken into account at all when determining the slicing of the rest of the part. Not good.
Looking forward to 5.0 where, no doubt, all of this is going to be hit out of the park.