I've never really found much difference between versions. I always use pimax IPD 55-57, my real IPD is 68. I find that IPD 55 in pimax gives me even better results than 57 but I also find this gives me much more eye strain, that's why i use 57, it's the first acceptable IPD. I don't wear glasses and my eyes are perfectly normal.
I think the problem arises when people have high real IPD, higher than 62. My theory is that because the Pimax has a hardware IPD of about 62 (the distances between the 2 lense cores), that people with higher IPD's need to have their eyes look inward. The point where the lines of their eyes then meets the screen is even further inward ('cross eyed'). So the higher real IPD one has (above 62) the lower the Pimax IPD will be. At least, that's my theory and I think it's about right because when I use my Homido lenses and use hardware IPD of about 68, then also my Pimax IPD goes to about 68.
So in short, I think this problem is caused by the fact that the Pimax does not have hardware IPD. I really hope the pimax 8k has hardware IPD, it would be a HUGE bummer if it hasnt ...