Kadet Max EDC or Knapsack ?

Lover or Chrome bags. They work very well in NYC. Been eyeing the Kadet since my K Sling is my most used bag in NYC. New rain version of the MAX eyeing me......

BUT I also own a very well made 3 day assault backpack. Do I really need both since an over stuffed MAX would basically be the same thing ? The MAX would be big enough to house a jacket during Spring and Summer for when I need it.

Thoughts ?

Thanks