I had heard that mills are rarely the exact size specified and discovered a couple of days ago that the 1/4" bit I got from Inventables is actually 0.247 inches in diameter (no big surprise there) which seems to have been enough to leave vertical lines on my carve. I think it would make sense if Easel would allow you to configure the actual size for the standard bit sizes they list so I wouldn’t have to enter a custom size every time - I could continue to pick the 1/4" bit size and it would use my preconfigured adjusted size of 0.247.
Of course the super deluxe version would let me configure the full list of bits I have into a library and let me pick the right one (in case I have more than one bit in a given size).