Another consideration should be given to the fact that for a number of reasons it can be an advantage having a permanent live at the fittings ie ext fans, smoke detectors, even a possible e/m light fitting. all possibles at a future date, with 3 plate. Also whilst it may simplify connections at the light fittings,to have neutrals at the switch, it will complicate things at the switch positions. I would only do this if neccassary, again just an opinion. Also any inductive/back emf sensitive equipment should be run in screened or shielded cables to be on the safe side anyway's. Again just an observation, we all have our prefferances.