So, I'm just happy! Myself working in the field of optics, although I had spotted the thoughtful design of these bulbs: LED emitters 4 a watt behind a molded plate playing double collector office (4 lenses) and diffuser ( a grainy structure made this office). The result is well above the majority of bulbs (LED or no matter): a beautiful light, pretty well run with a good color (warm white) and without super bright spot that make them so painful LED watch in the long term. So I'm really conquered, and more these bulbs really have a good luminous flux which comes largely from the way light is used: yes, it is well used 310lm widely enough to perfect lighting. Nothing to do with the low-end models. And when the price, I now found surprisingly low compared to the product quality.
A recommendation, however: these bulbs are for a relatively remote lighting (in my opinion> 1m) because their issue is relatively powerful and directed lighting. So I would not recommend their use for a bedside lamp though I could be wrong.