I have managed to solve most of the problems with our Dual Extruder V3. Unfortunately it involved custom machined parts and the use of an $80k Markforged printer.
I made a new, much taller and far closer fitting heatsink to solve the heat soak problem. Then I reprinted the Dual Extruder frame using carbon fiber filament so I can use stronger springs, along with moving the filament spools to the top of the frame to reduce the chance of filament grinding. I redesigned the Y axis bearings with aluminum housing and ultra close fitting Delrin bushings, this mostly eliminated the table’s tendency to push down slightly when probing and wind up offsetting the head too far down. This also allowed better stability to check and adjust the extruders with a height gage I designed and printed.
I still have loads of problems with Cura, it loves to change settings around which is super annoying considering there are so many.
The purpose of this post is to show how poor this head (and frankly machine) is, it is pretty much unusable out of the box. I would like to go on an on with the many problems that remain with Cura but I think this post has gone on long enough.