Ogryn feels very bad to play on higher difficulties if you are not running the shield. Enemy gunners eat him up for breakfast.
I propose changing his passive from 20% damage reduction from melee/ranged, to just 40% damage reduction from ranged specifically. I feel this will make him feel a lot better to play on higher difficulties and allow more weapon viability to exist for him.
An additional positive change would be allowing the Ogryn to complete the data-interrogator puzzle while taking damage, and be able to carry the power-cell while taking damage, similar to how he can revive teammates while under attack. It would help cement his place as the support character, and provide objective-based benefits for running him (such as being able to move powercells quickly) in more game-modes, making it less situational.