Choice of surgeon is the most important consideration, regardless of the method employed.
He will have a huge influence on the overall outcome, short term and long term side effects: nerves will suffer some trauma during surgery which can result in short term disfunction.
One of the main aspects of long term ED is whether it is possible for one or both nerves be spared, and if so the surgeon's experience and expertise with nerve sparing techniques whether he is performing open or robotic surgery.