Here is a way to defeat curling/warping in your prints.
The term might be taken, but I call it a "Brim." If anyone wants to coin a new term for this, make a suggestion ;)
Using the program Slic3r I add a "skirt" of 5 to 15 loops at a "zero" millimeter distance from the object I am printing.
This adds a brim (like a cowboy hat ;) ) that keeps the object "spot welded" to the plate and absolutely stops all warping and curling.
The additional surface area, combined with and rounding of sharp points on the bottom layer denies any possibility of curling or warping from the bed.
To remove the brim, you need simply fold the plastic back and forth, and it snaps off :)
I hope to see this method implemented in the various slicing programs; as its own unique feature.
Try printing with a Brim today, and see if it helps the quality of your prints ;)