There's a thread in the Trouble Shooting & Bugs section that is allied to this subject:
viewtopic.php?f=9&t=11769
When the Variable Settings Wizard was introduced, the bottom and top solid layers at the interface were prevented from being printed...and the top number of layers from the highest profile was adopted for "real" top surfaces throughout the model....and a similar thing for the bottom solid layers.
The above feature request is for solid layers to be specified as user defined heights....and I suggested using the redundant number of top/bottom layers as an indicator for user-defined solid layers.
I think if the devs look at all of these different requirements, they could produce a one-fixes-all solution!