This has been a common discussion with a good friend of mine. I use a Z shaft and he believes that when trying to hit center ball a miss hit with a smaller shaft puts more english on the ball than a larger shaft and potentially throws the object ball farther off line. My argument has always been the contact patches are the same so a small tip does not put more english on the cueball than a larger tip.
I agree with your friend, larger tips are more forgiving.
The one instance I do feel a smaller tip could produce more spin than a larger tip is when we are talking about draw. A common cause of miscues when trying to draw is when the tip hits the table before the cueball. A smaller tip would allow you to get lower on the cueball without touching the table than a larger tip would.
This is the tradeoff for the extra forgiveness of the larger tip.