On paper Gut should do more damage because of the dot
That's not even remotely true. Energy Blast is off of the GCD so it is, quite literally, free DPS. Gut is on the GCD so, if you're actually comparing worst cast, it's Gut v. Hammer Shot + Energy Blast for combined damage. Energy Blast + Hammer Shot actually deal *more* damage than Gut, and that's completely ignoring 2 major aspects of it: Gut is a Dot, so it's *delayed* damage rather than up front damage (delayed damage is worse for a tank because you want threat right away) and Gut ends up costing 3 more Ammo than Hammer Shot + EB (since EB returns 1 ammo and Gust costs 2).