People with more experience will know better than me, but many people say that today's technology means that most 4 pieces will perform comparably to 2 piece rods. The difference, were it to be noticeable, would be in the rod's action. I have 3 4-pieces, and even with the mid flexes I have not noticed any interruptions in the flex. Plus the rods travel well!
And I'm late to the party with my response