Brutus argues that in a republic, "the manners, sentiments, and interests of the people should be similar…if not, there will be a constant clashing of opinions and the representatives of one part will be constantly striving against the other." should a republic be made up of a small group of like-minded people? or, is diversity of opinion beneficial to the success of a federal government?

Brutus' vision of republic is outdated. Diversity of opinion is vital for a republic.

It's necessary for a republic to have people who represent all kinds of people in it. Different classes live different lives, and it's hard for a person who belongs to one class to be aware of the needs, manners, interests of people from a different class. For this reason, diversity is a very important part of a republic.

A republic should NOT be made up of a small group of people who think in a similar way. On the contrary, it should be made up of people from different backgrounds, in order to better represent its people.

both include an amendment process.