Old eyes are a factor. Without special glasses, for iron sights, I can't shoot a 25 yd head shot. I just can't see the target and the sights accurately enough with my walking around progressive lenses.
While it's unlikely I will need to make that shot, It's also unlikely I will ever need a carry gun. My normal carry is a P10C with a dot. I compete (USPSA and IDPA) with a dot. I am in the market for a Shield + with a dot, though I don't want a performance center gun. Particularly for the medicare set, If you practice with it, the dot makes you better.