Certainly when it comes to camera equipment, nothing has to be forever. As another member pointed out, if you find out that you do not like the 25mm lens or using the auxiliary finder, you could sell it and purchase the 28mm lens. If you were to use zone focusing on the street, by the way, you could simply bring the auxiliary viewfinder to your eye when a picture presents itself, without having to look through the built-in viewfinder on the camera, frame, and shoot.