According to Birkholtz, after 4cm complications increase exponentially.
6cm is generally seen as much safer than 8cm, and between 6 and 8cm your change of complications , and a much longer recovery significantly increases.
Those who have done 5-6cm on femurs recover much quicker than those who do 8.
But consult your surgeon. This is not medical advice.
Oh and get an ITB release. The 'soft' ITB relase is NOT an ITB release, those are pokes , not a paartial cut on the ITB band.