Everything depends on your limits and what you're trying to do with said discs. You won't know if you have the arm speed and form capable of utilizing a heavier disc until you throw that disc alongside your lighter ones. Ultimately, the heavier disc is going to have better distance potential if you have ability to utilize it. Partly b/c they have more mass, partly b/c they're less affected by wind.
Weight and Form: Lighter discs are easier to get up to speed and display their flight numbers than heavier discs. So if your arm speed/form is lagging behind a 175 Buzzz, it will fly more overstable than its flight numbers indicate or as a 170/165/160 etc Buzzz would fly for your arm speed/form. If so, it won't necessarily hurt your form, it will just be "beefy" for your arm. The paradox of learning how to throw discs is that in order to throw discs well, you need to learn to feel the "hit" and to maximize this feeling. Yet the "hit" is easier to feel with heavier discs b/c more weight is concentrated along the rim. It's all leverage. It's easier to feel the weight of a sledge hammer come around (leverage) than it is to feel the weight of a ball pin hammer. But to throw the sledge farther than the ball pin you need requisite strength and form to really sling it. For most beginners, the lighter discs are better b/c they don't have the form necessary to fully incorporate leverage. The lighter discs can be thrown faster with worst form/less leverage.
