Well, it would certainly be of full interest to the team/mission for me to be on the team I'm best suited for, the team I'd be best at. When I say "get the most out of" I obviously don't mean it in a transactional sense
Everyone involved in SOF gets something out of it, it would be absurd to imagine not, otherwise no one would do it. I don't mean money, I don't mean glory or any of that nonsense. I'm talking about exactly those things you list in your post about "Why do we do this?".
Right now, at this point in my life, I am thinking about where is the best place for me to go to find "Humility, maturity, emotional/spiritual/psychological toughness, self sacrifice, intelligence, self control, ability to negotiate, Team work, self reliance, physical fitness and the abilty to lead or follow as required"
Of course you can find these at any SOF unit, but really the ideal situation is to find myself at a unit where I can best align in terms of values, character, mission set, and world view. I happen to be of the opinion that it is important for me to understand a unit to the best of my abilities before pulling the trigger and enlisting or attending selection or whatever. That includes both basic things like understanding how your career evolves and is evaluated and more nuanced ideas like the culture of the unit or the vision its commanders have for its place in the military. This is especially relevant because I am looking at two units with pretty substantially different mission profiles.
Sure, I can never know everything I need to know about a unit until I'm there, but I can definitely make an effort to learn what I can, so I can avoid wasting anyone's time when I show up and ask them to try out