Easy
,Get the 9.5, then when you discover its too big(OR GLUED OUT OF ALIGNMENT AT THE FACTORY) trim it down on successive occasions until it's about right,when you may discover you now have the wrong shaft length in relation to blade size adjust it up,down,up down etc(depending on what gets sore 1st,back or shoulder.
Takes about 8 mths of tinkering to do it this way
When the adjustments start to decrease your performance,buy a new one at exactly the right size ........ if you can rememberv what that was,
like i said,Easy
ps youll most likely be on an 8 by this stage anyway
l lead a very sheltered life