I'm down. This would allow Sentinels a chance to cross open areas and get into close range (closer) but still not strong enough where they they can just walk through a hailstorm of gunfire unfazed.

However, I believe, like the cloak, there needs to be a mechanic put in place to delay a swap from shield from weapon and vice versa. If a Sentinel can instaswitch from an HMG to a Shield, walk through gunfire, then swap right back to an HMG and start firing, it would be ridiculously OP. There should be a delay swapping to AND from it of like 1- 1.5 seconds. Enough time so the individual can't use it as a "get out of jail free card." If you are already being fired upon, you shouldn't be able to just pull up a shield and save you from being killed. Likewise, you shouldn't be able to just sit being a shield, wait for the enemy to have to reload, then swap out and insta-gank them.

Another question. While in use would it cause a movement penalty (either x% to movement or, like crouching, not able to strafe)? Either of the two would be O.K. Since it is basically a riot shield, you can still move with it, but are unable to move as fast.

If you want to add a little flair too it, give it melee capabilities:

Shield bash. Melee range. 250 for light, 300 for medium, 350 for heavy, 400 for officer.