Thanks again for your answers.
But I repeat, I already have a little experience playing omaha.
In fact, I have already won some Sit&Go playing Omaha.
I'm searching for people that have used counting systems and can talk about their own experience about those systems.
By example:
There is a counting system created by Mr. Hutchison, but also I have read some critics on that system, indicating that the form to score the hands is not the suitable one.