No, it's the same, no difference.

Sometimes, they will be very fast at 5*. After that, they are "normal" FT.

I also bought few 4* FT, because they were, what I wanted/needed. They have only one "issue": the need green, to bring them up to the rest. Since the cut of the greens you can earn, for me, they have to be really good (at least to positions and SA, I need) to buy them.