I am in the market for a new spotting scope and I have narrowed it down to the vortex viper and razor. Is the razor worth almost double the price of the viper? The second question I have is the 15x45x65mm vs the 20x60x 85mm. Both models come with either package, for judging deer/elk at around 1,500 yards is the 45x65mm enough? Does the 85mm low light capability justify the extra size and weight? I will be doing quite a bit of hiking/packing with the spotter so the size/weight of the 65mm seemed favorable but if the 85mm is substantially better then it would be worth the extra weight to me.