Just a quick follow up to the previous post. I did measure the difference between the stock light bulb and the Narva +50 Longer Life, much as the limitations of a mobile phone allows it.
The stock bulb measured at four meters distance on the brightest spot as 2350 lux, while the Narva +50 Longer Life measured as 3010 lux. Finally the numbers are showing +30% (with a bit of a round-up) brightness for the Narva bulb.
Always take numbers and measurements from manufacturers with a pinch of salt.