5X, I don't have much experience with the TFO rods. I have cast a couple at a shop a while back and they are nice. I know several builders who build a lot of TE rods. I have not heard anything bad about them. I'm considering one for a quote for a customer.
4 pc. vs 2 pc.- I have heard it said it takes an expert to tell the difference in action. Personally, I really don't think there would be a lot of difference.