As there is not much going on here yet, and my own projects with EV3 are not working out as I would want, I'll post this video from someone who designed a 6 DOF with 1x RI.
He used my program I made to be used for a 6 DOF with 2x EV3 and changed it to work without homing sensors, as it has only 6ports, each needed for a motor. With my help explaining how I build up the program, and how he could make it work and what changes would be needed. He did manage to get the forward and inverse kinematics working, allowing the 6DOF to make straight lines and smooth movements, each axis motion ending at the same time.
Before he started I thought the calculating power of the RI would be to slow, but it seems to be even faster than with EV3! Cycletimes are faster allowing smaller intermediate steps.
If I had a RI I would try to make this aswell to compare the EV3/RI 6DOF.