normally what I do for all my profiles in Slic3r is set the first layer height the same. This allows the first layer to print no mater what the layer height is set to. My default has been .35 and has worked very well.
I have found with Simplify that the first layer changes to whatever you are doing for layer height. If I am printing 50micron. I get a 50micron first layer. This does not want to stick at all. I have worked around this issue by creating a process for just the first layer and a process for the rest of the print.
This should be something that is modified under the different plastic types. A default first layer that can be a hard number or a percentage.
I will not go back to just a single process. I have a job running now where I have a .3mm first layer and a .1mm second layer process, and it is the best first layer print that I have seen so far.