You say that under boring can break paint. I've under bored for years, and I've never had any issues breaking paint. I usually don't go so far as to use a bore size where I have to use force to push the paint through, but maybe I'll try that next time I go out, just to see what happens.
I also don't feel that under boring will clean barrel breaks either.
I honestly don't ever see a reason to over bore because of the reason I stated above. If given the opportunity, I will always under bore.
finally, you have a funny accent. "qwarta" hehe.