Should my PFR% be lower at the lower limits?

don't be so passive. not raising good hands because you think you're going to eventually get outdrawn is poor strategy. push the edge when you have it. raising TT or JJ depends on how many opponents you're up against and your position of course.
you make money when the singleton ace or king holders don't fold and don't hit their 3 outer. if raises don't thin the field of these players, and an ace comes and there's a lot of action, you can know you're beat at least. (for the most part)