I have a TCS EU621 decoder fitted to my E5004, the only lighting anomaly I had was that F1 worked the reverse direction cab light and F2 the forward one, easily sorted by reversing the decoder direction in CV29. Both headcode lights come on with F3, but I think that is how it's wired.
Movement is very smooth although I've only tried it on the rolling road and a very short piece of track.
Al