I printed “corner block” (international edition) first with PLA and then with ABS, just to know if I get different results. Indeed there’s a difference in dimensions. It seems that ABS is shrinking too much.
As you can see the diameter of the PLA version is 25,04mm, so 25mm conducts fit perfectly. Printed with ABS, I only got an inner diameter of 24,35mm. Using the ABS version would lead to brute force when trying to get the conducts in 
The outer dimensions also differ and the ABS one is always a bit smaller.
By now I can only recommend printing the parts with PLA. I see no advantages of using ABS, especially cause PLA is much more easier to print and has the same strength. The only advantage would be a higher temperatur resistance - but that is not needed for the CNC.
