Well if you dont have similar products and not experienced a failure with the type of root cause given, then i like to state 2. Never choose 1. As
FMEA is an continuously and ongoing process, later if you face NC?s that is based on the root cause given, you can raise the value and make sure there is some kind of history log in your FMEA.
And yes FMEA is still there to prevent failures, but for which price?
Some potential and theoretical failure modes based on their root causes can sometimes really be hard to set any value on it. The most common failure is anyway that people spending to much time with discussing the values instead of focusing on keeping it simple in the beginning and listen to feelings.
Also some customer don't understand the FMEA process and bomb you with RPN targets that do not really make sense as RPN is only a helping tool to organize your FMEA. I would rather look at how severity is placed in relationship to occurrence. Also i like to focus to eliminate human error factors first, while i often see that people rather invest $$ in detection.