I like to run 6K stamina for my shield instead of the typical 9K. I feel like I shoot marshmallows when running 9K stamina. 6K allows me to put more into firearms to hit harder and also unlock more weapon talents to further hit harder.
As long as you play smart, don't get too overwhelmed, you can use your healing station when at full health to heal your shield or a medkit with combat medic to heal your shield as well.
6K stamina will give you a shield with a little over 1 million health vs 9k 2 million hp shield.