Based on the text you've read, does Locke think that one type of government versus another is more susceptible to becoming tyrannical?

I don't think Locke believes that one type of government versus another is susceptible to becoming tyrannical, but I think that Locke believes they have conflicting interests. Those conflicting government issues and interests will eventually lead one government to one dominate the other.

Locke states in section 201 that it would be a mistake to think that tyranny can only occur in a monarchy. Though he is writing mostly about the monarchical system of his country, he brings up other examples of governments that had tyrants, including ancient Athens, considered the world’s first democracy, and ancient Rome during its republican period. He states that power in any hands that is used to "impoverish, harass, or subdue" will make the use of power tyrannical.