It's not that the absence of gravitational fields slows time up relative to observers in more massive reference frames, it's that the presence of gravitational fields speeds up time relative to observers in other reference frames.
You would age about the same as you would in microgravity. You could get closer and closer approximations by going into Earth orbit, solar orbit, and galactic orbit. Each approximation has less gravity, so time would pass slightly slower relative to an Earthly observer at each step, but the effect diminishes.
I understand, but the corollary of time appearing to speed up close to gravity well (article explains this is not a field per se) is that it would appear to slow down further away. Is there a minimum speed of time relative to earth?
You would age about the same as you would in microgravity. You could get closer and closer approximations by going into Earth orbit, solar orbit, and galactic orbit. Each approximation has less gravity, so time would pass slightly slower relative to an Earthly observer at each step, but the effect diminishes.