Sorry for answering late - Currently I use these settings: Dual Extrusion Head: Heat creep? More likely: Bad feeder! - #11 by Hauke - not perfect yet, but I’m getting closer. I do not print very often (have only done 5 prints with DX yet), so my iteration is slow.
With these settings I get a decent first layer: [First Batch Shipped Out] FAQs of Dual Extrusion 3D Printing Module for Snapmaker 2.0 - #152 by Hauke - but you can see my blue also has an edge problem. I guess I’ll increase extra prime amount even more after extruder change. Note however that I do not use a prime tower.