Stitchscape blends multiple terrains together easily and seamlessly, or a single terrain can be made tileable. Whether they differ a little or a lot, any number of terrains can be stitched together instantly (visually speaking, that is...they remain separate terrain objects).
Just set up your terrains in the Stitchscape wizard (automatically or manually), decide how big the blending zone should be and how much blend strength to use, click “Stitch”, and you're done! Saves hours of time.
In addition to the editor tool, you can stitch terrains at runtime as well, using a simple function.