Update:
Printer is running fine now,
Electronics:
-Rumba Board with full graphic display.
-The 2 Y motors are wired parallel, on 1 stepper output, works fine, rest is default, 1 output, 1 motor.
-Extruder lights and fans are wired parallel, of fan 2 output, they switch on when 1 extruder is above 50 degrees.
-Parts cooling fan is wired on fan 1 output.
-Heatbed (220V) is connected true a solid state on the default heatbed output of the Rumba.
Nozzles:
-Designed adapters for the use of E3D V6 on the extruders. With a spring around the shaft, so calibration of the nozzleheight is easy.
-Tried a combo of E3D V6 and E3D V6 light version, did not work optimal, you can't use the speed advantage of the full V6 version, (software only allows 1 speed for all the extruders), so changed to an all E3D V6 full version, works much better.
-Have to add, i removed extruder 3, just to reduce weight, and probably will never use it.
Software:
There is no Cubex profile for a Rumba / Marlin combo, so i had to build one myself. Had a lot of things to tweak, but in the end, works, super with 1 nozzle (more is a problem, explenation on the bottom of this post)
Overall:
-Removed the waste box and its 2 mounts, because the nozzles are to low, and can collide.
-Mostly feed the filament directly in the extruder; the pipes running true the machine are not so easy to use

-To remove filament, i always push out 10mm, followed by a retraction of 100mm, works fine.
To Do:
-drill holes (4.2mm) in the bottom part of the extruder, so the filament guide of the E3D can go up to the extruder wheels, needed for reliable flexible filament prints.
-Look for a solution to use a longer cable so i can put the display in place of the Original (now the cables are 30cm, not longe enough, and longer cables give a lot of problems)
-Program + wire an output of the Rumba for auto switch off.
And i have 1 issue with 2 color prints, which i think is a S3D related problem.
The second nozzle is not retracted after the purge, so you get a mess on the first layer from a leaking second nozzle, while first nozzle is printing . Once past the first layer all is well, oozeshieId an primecube works ok. I am not alone with this issue, i found a possible workaround, but had no time to test it out.
It was a lot of work, but in the end, the printer frame makes it worth it.