KOPS is a starting point. For me and fellow riders I've checked, the most common thing for road bike position is to drop the plumb bob from the bony protrusion on the front of the knee just below the knee cap. From there, mess about until you seem to be developing your best climbing power with your current musculature, assuming a road bike fit. Since there are so many different sorts of bikes and therefore different sorts of fits, I doubt that one fit is more prone to injury than another. And "efficiency" is too loose a term to even enter the discussion. You want power at LT or FTP. That can be measured.