Hello, I'm looking at the Vortex Viper PST Gen 2, and can't decide between the 3-15 and 5-25. I will mostly use it on my .223 AR on steel plates out to 500-600 meters (550-650 yards). Later it may also be used on a 6.5 bolt gun. I'm thinking the 3-15 is more at home on the AR, but I wonder if I'm missing out on something with the 5-25 which has more magnification. Will the higher 5.25 magnification be useful in stages with unknown distances where you have to mil the target? Will it be better in low light? Does the 5-25 have a clearer image on 15x?