When using mono poly you should have your upper tension on the loose side because of stretching. This is such a thin thread you really don't want to stretch it.
If you use a polyester batting when using different color of threads, this will help with some of the "pokies" While mono poly is a soft thread, I don't think I would be doing a stipple stitching with it. Stippling beats down the area and has a tendancy to make the area stiff, then add the mono poly will only make it stiffer.