The downside is that they have stipulations in their tutoring abilities like Demonic Counsel requiring you to have four or more card types in your graveyard and Diabolic Intent forcing you to sacrifice a creature to go digging, but thats not really a problem in most games
There are also some powerful cards in Boros to consider, including Orthion, Hero of Lavabrink, Duke Ulder Ravengard, Bruse Tarl, Boorish Herder, and many others
Jarad is a synergy rich card that both loves filling graveyards and benefitting from their full state
Cards that deal as little as 1 damage will still benefit from your commander's effect and can deal huge damage
Overall, Damping Sphere gives us a 2 mana play that doesnt hurt too much and still punishes most of what we wanted to hit with Null Rod
This puts a lot of pressure on your opponent to remove Ursula promptly