I played the 4D 300 for many months and then tried the Biomimetic 300. For me I liked the 4D 300 A LOT better. It doesn't have the maneuverability of the Bio 300, but it has a much more solid feel, and due to the higher swingweight it seems to have more pop...especially on the serve and on my backhand. I feel the touch and control are also a great deal more with the 4D 300. Again, these are just my opinions.
Enjoy each moment you're allowed to be on the tennis court!!!