Thanks for the reports everyone, very helpful!
- The bearing holders for the current version (1.4) have a diameter of 19.1 mm. I will increase this to 19.25 mm for the upcoming version, it should be fine for all bearings while still sitting tight enough. I do want them as tight as possible and the carriage shrinks a little when printed.
- The bearing placements were adjusted in version 1.4 to sit further apart based on user feedback and from my own measurements as well as compensation for thermal expansion (well thermal dilation in reality as it shrinks), it looks like I went a tiny bit too far as they possibly push the rails outwards a bit but in my case current version is good. Originally it was the same as Chad's version (which is 69.514 mm, I increased it to 69.80 mm). I think I will set it to 69.7 mm.
- People will just hit print so I must adjust this in the model, it's not as easy as measuring and designing and expect people to compensate for thermal expansion because they won't 
- Version 1.5 will have a removable dial holder.