Successful slight enlargement of Axoloti mounting holes --
Hi there, I realize this post was more than a year ago but I wanted to contibute something on the topic of hole-widening. I have just widened my holes to the diameter of a #6-32 screw. There was no problem at all, but I would not use a screw any larger than this. On the top of Axoloti board #6-32 screw head clears any vias and components, but even a washer much wider than this may be wide enough to touch an SMT component.
How to tell if it's OK? I have board revision 1.2. If you hold the Axoloti up to a bright light, you can see through the board in all places where there is no copper plane. If there is copper plane in any layer, it will fully block the light. So with this method you can see what the tolerance can be for widening or altering the holes. It's not much, but there appears to be some.
Edit: For users in metric countries: the #6-32 screws I am using have a major diameter of 3.4 mm and a head diameter of 6.5 mm. But I certainly would not widen holes any more than to 3.4 mm!