I am seriously thinking of getting this lens but I will wait for one to be fitted to the next Gopro. Yes you can remove the fisheye from the standard lens but the sides of your image will appear mushy. Apart from there not being any fisheye, so no post processing to move it there are 2 further huge advantages.
1. Your picture appears much closer to the subject than the standard lens. This allows you to keep to local rules on flying distances and still get a good closeup shot.
2. No fisheye when you tilt. Tilt shots look awful with the standard lens, Now they are beautiful.