I didn't step down but returned as a barista. I agree that you definitely have some room to negotiate on wage based on your experience/knowledge. You also have lots of experience to offer other baristas around you. Make the best choice for you.

Before you step down, try lowering your availability if you can. School takes time and if you have some to shave from being at the store, do it! If not then stepping down should only help a little. I mean a good SSV should have hands on deck and help the crew but should also do a fair amount of delegating tasks so everyone aboard shares work load as best as possible

I haven't stepped down but I've known people who have! Make sure you negotiate a higher wage for yourself!