The sweet-natured hero is one of Heyer's classic character types and a welcome change from the alpha alpha alpha alpha male that literarily dominates romance literature.
Darcy and Rochester are far more common than Bingleys in most romance literature.
Granted, Darcy is more introverted than consciously pushy. And Rochester is a big marshmallow wrapped in all kinds of denial. But the Bingleys are often secondary characters.
In Heyer, they have their own books!
One of the best examples is the Duke of Sale or Gilly from The Foundling. His parents died when he was a baby. He is raised by his uncle who is a blustery, domineering man whose fundamental goodness is demonstrated by his care of Gilly. The uncle is, after all, the heir to the estate. Nevertheless, he raises his nephew with all the assiduous attention that frankly, he doesn't force on his own son. He coddles Gilly through his illnesses. He hires dozens of servants and companions who adore Gilly. He manages all Gilly's affairs "for his own good." He honestly believes in his duty to raise this child successfully to manhood.
The sweet-natured boy grows up to be a sweet-natured man. Eventually, he rebels at his constant "handlers" and escapes on a series of adventures of his own. He comes through with flying colors and even learns to stand up to his uncle.
Where Heyer excels with these heroes is that she doesn't turn them into shouting, domineering alphas. They retain their gentle natures. They just learn to go their own way and insist on their rights. Gilly is, after all, the Duke of Sale.
It is quite honestly difficult to find these heroes outside of Heyer and M/M literature. M/M literature has quite a number. One of my favorites is from Jackie North's holiday novella, Hot Chocolate Kisses, in which fussy (but not OCD), homebody Cory--who loves Christmas and gets particular about people taking their shoes off in his home and reads Charles Dickens aloud--has a core of toughness that gives him the chutzpah to stand up to the police on behalf of his once criminal boyfriend, who has a definite Rochester vibe. The relationship is entirely believable. A noteworthy comparison: Heyer gives Gilly a cousin, Gideon, who is his best friend and one of the few people in his life to believe that Gilly has the fundamental strength to be as tough as he proves to be. The relationship in Hot Chocolate Kisses is not dissimilar. 