So I will bet that somebody will post up with some sort of formula or rule of thumb to put you in the right position and justify it with some sort of anecdotal story.
I just had a paddling lesson with an ex Olympian with the goal of discussing theses type things and having them point out how much I suck at technique and show me how to do things better.
The topic of leg length was discussed with the opinion of my tutor being that it is totally what you are comfortable with.
If you want em short, run em short. If your comfy long, then run em long. Everybody is different and will find their own length.
What ever allows you to be comfy without hindering rotation.
The impression I got was that leg length was about as important as how many scratches you had on the deck of your boat........
So no doubt, various body proportions and flexibility or lack thereof will influence what length you run at, but from what I was told, doesn't matter.
Follow the path of the independent thinker. Expose your ideas to the dangers of controversy. Speak your mind and fear less the label of 'crackpot' than the stigma of conformity. And on issues that are important to you, stand up and be counted at any cost.--- Thomas J. Watson