If you have a bow I find upper dungeon is completely trivialized by that alone, no need for strafe attack. Additionally, a bow greatly multiplies the power of disengage 2: You can put everything into kill range, and keep 100% uptime on your SP by always getting the points back. A bow and disengage 2 is far more powerful than a bow and strafe attack in UD. Disengage 2 is all about letting you use those more powerful abilities more often, that's why it is essential imo for a duellist to get it immediately.