Yeah, I can see what you mean now, because 3/8 of the time 3P0 fails, and hence he doesn't 'work'... so from a pure numbers effect I see what you mean. That being said, when I think of spend 3 points for 3P0, I think to myself, this will guarantee me one evade a round. So pass or fail, the effect is still the same.
I still think 3P0 is hands down better.