Nick,
your answer makes sense to me.
let me explain : i may be a litle too concerned by the "airfoil" thing since i've always read all the critical studies stating that the airfoil is "THE" holly grail. i think it has too uch importance in my mind.
I really prefer to know that the most important is the rotor as the "mechanical" system instead of a pure aerodynamic system.
My actual choice is : 2 blades or 3 blades ? the challenge is different, but i think it is worth a try if it makes a real improvement without restrictive problems.
I won't chase the few percent since i know that i can stay simpler and easier with a proven design.
for info the Max weight i talk about is 540 lb, single or 2 seat. I don't plan to design something bigger.
I just try to do correctly my homework instead of taking an existing empirical solution, meaning : buying an existing 2 seat rotor.
With humour, i'd say that designing a rotor with inertia is not a problem, nor to do a strong rotor.
the problem is the "light enough".
Thank you for your patient explanations.