Thanks John for you exhaustive reply. The problem for having 4 alibabas on different "colors" is you should have 2 alibabas on the first row and 2 on the second row. But the majority of CVs has just pawn on the second row.
Anyway I would like to know if there is a general formula to determine the piece's value on 8x8 board with FIDE rules. Or a table with the values of the most common pieces.