I`d say that depends if you get the right ones. There`s a wide range of LEDs on the market and some are worse than normal filament bulbs. Which ones are you using higgy ?They are an obvious improvement ...
Hamish, while many rules and laws can be questioned they are what they are. Testers may notice or not but even if they don`t it doesn`t make something that isn`t permitted legal. You never know what insurance problems you can face if something happens and an expert says the vehicle isn`t fully legal.
I guess that`s the main issue. Everyone will have to decide for themselves ...