I've an opportunity to purchase a 45mm PC lens with 4+ yrs on the warranty but I'm torn between this lens and the 24mm lens. Does anyone have any thoughts on this lens vs. the 24mm? I realize Ken "I know everything" Rockwell claims the 24mm is better but according to his write up he's never actually handled one (and amazingly this does not prevent him from having an opinion) and I wonder whether the additional couple of stops makes any difference?