I upgraded to the phantom 3 professional
I do a significant amount for water/ boat video and photography
Yesterday while flying over the water I received a return to home because the drone was to far from the home point for the battery. Low Battery Return Home. I was over 2 miles from my home point. I had the drone  running next to the boat at all times less than 100 feet from the remote control. I was able to get it to emergency land on ground and save the unit!
I there a way to stop return to home for insufficient battery???

I am just a noob but in the manual  A) you can still cancel an automatic RTH by hitting the RTH button on your controller or hitting cancel when your App first displays the warning. And B) you can still alternate course and altitude on a RTH to adjust for obstacles and such.

I too was wondering about this issue and I went out yesterday to an open field to try it out and it seemed to work fine. I also practiced maneuvering and adjusting the landing point when RTH was engaged and it was pretty simple as it comes down really slow.

What you needed was dynamic home point.  (It uses the current GPS position in your phone or tablet as the home point.)  This way you can be on a moving vehicle and the drone will consider your vehicle as the home point.

However... DJI has not implemented this feature on the software yet.  It is a promised feature that's not implemented yet.