I was terrified of this new enemy upon hearing about him, and still am after encountering him. I think he’s a great addition to the game. Like other shielded enemies, he prevents you from just chopping through the horde, but UNlike those guys, he doesn’t get knocked back as easily, forcing players to back up or move in a separate direction, succeeding in your design goal of splitting the heroes up.
The shield doesn’t feel like it has an obscene hitbox like Bulwarks used to have, and the stomach weakspot is an interesting choice that lends itself very well to baiting out a swing or just hammering away at him. While threatening, I agree with @Slayerkin above about how the two heavy elites fare in hordes.
My only real complaint here is that the shield bash attack does damage when it doesn’t feel like it should, as it functions like a push other enemies do. I understand it’s a giant slab of metal, but it doesn’t look like an attack to me, and feels unfair to get hit by.