I am considering a Vantage 90 SI, 330 grams, 12 points head light. I find it difficult to decide on the stiffness on paper. I have read that I should lower the listed stiffness of 70 or 63 by a few points after the frame is strung. Can anyone comment on power level and crispness? How does 70 RA or 63 RA compare with for example a PS 6.0 concerning feel? i am tempted to 70 RA, however, it should not bee too harsh or stiff, like a K factor 95 for exapmle.. Can anyone advise or comment?