Hi pancholiph, one always wants to avoid singularity, because any robot moving through singularity will have a shortened life span on the 4th and 6th axis. I don't really know where one would find such information. All I can tell you is that the speed reduction will help as the robot will not move at full speed through the singularity.
I had the same problem with a glueing application on car side frames, where the cell space was just too small not to move through singularity.
Good Luck!