This is awesome! You just put a smile on my face :) I never thought about this before because, as you mentioned, reblogging is typically a "one-click" action that doesn't require much time or resources.
I see the value of reblogging if the person doing it has a good number of active followers with a strong amount of HP. It makes rewarding rebloggers worthwhile. With the conditions you're planning to implement, you're taking the decision of who gets rewarded out of the author's hands (unlike with @commentrewarder). To me, this is great because it encourages rewarding meaningful reblogs. It also reassures me that those being rewarded have a legitimate reason—to boost the visibility of the post, gain more engagement, and possibly earn more upvotes.
For me, Example 2 is the option I'd go with, especially with the added condition @arc7icwolf pointed out.
I don’t have anything to add, haha! I like to think of myself as more of a creative person than a mathematician 😅.
Lastly, I’ve been using @commentrewarder on all my recent posts, and I’ve already noticed a positive impact on both rewards and engagement. I’ll definitely use @reblogrewarder as well—I think they complement each other perfectly in helping boost a post’s reach. Thanks for continually expanding the possibilities and making this platform even more exciting!