Fujikura Rombax F ?

Hi guys i was wondering if any of u using Fujikura Rombax F ... N which model ? any good . im thinking of puting for my dad which is a 5 handicapt ..... he hesitating between 5F09 And 6F09 Stiff ....

The 5F09 have a torque 4.0 n weight of 56.5g , but the 6F09 has a torque 3.5 with 64g ... my dad use to use a 3.5 torque with 59 gram will be much difference ?