I assume you meant "more ethical" rather than "more efficient"? In other words, the correct metric shouldn't just sum over QALYs, but should assign f(T) utils to a person with life of length T of reference quality, for f a convex function. Probably true, and I do wonder how it would affect charity ratings. But my guess is that the top charities of e.g. GiveWell will still be close to the top in this metric.