I rarely use moderate profile implants as they do not provide enough projection. When you consider that you are placing the implant under the muscle, breast tissue, and skin, the profile of the implant is flattened. The heavier and the more dense that your tissues are, the more this phenomenon occurs. Generally, a moderate profile implant will give you a low profile look, a moderate to high profile will give a moderate profile look, and an ultra high profile will give you a high profile look. As far as Allergan Natrelle implants, they make that same profiles as Mentor. In fact, their new Inspira line has the best range of shapes and profiles of all manufacturers. I hope that helps and best of luck to you.
The profile of the implant should be based on your existing anatomy and your desired result. Personally, I rarely use moderate profile implants. I feel the do not provide adequate projection in many women. Allergan does make implants that would be considered moderate plus profile.