By rights I think that there should be an option or even a special ability on PES 4 for being able to use both feet.
I have his weak foot ability on 8 as I feel it's deserved.
I can only think of Waddle on PES of the top of my head that deserves an 8. Zidane is about a 7 but maybe I'm being harsh becasue he has scored some good volleys with his left.
On a side note I'm actually ambidextrous but I am better at different things with each hand/foot.
Like with football for instance, from a dead ball I will use my right foot apart from for penalties which obviously (through powers of deduction) I use my left which is also better for vollying.
I prefer my right foot for short passes and my left foot for longer ones but I can tackle with both. My foot used for my first touch changes (when I have enough time so accomadate my preference) depending whether it is on the floor or in the air. Left for the floor and right for the dropping ball. lol! I said "dropping ball".
It's the same with my hands as I w.............rite with my right hand and throw with my left.