Subjectively, super light, but does not meet all of the specified techn. Values

Did my first LED filament lamp (COB) gained as the rel. new technology sounds promising.
The lamp has a very pleasant light, a glass flask (not plastic) and electronics (if available) will disappear completely in the E27 screw. In this respect firstonce very positive and nice "classic" to look at, just in open luminaires.
The only my brightness, or the amount of light emitted / the luminous flux appeared somewhat low, and so I gained interest, even let the technical data measure.

Positives:
+ Light color (warm white, 2700lm) is satisfied
+ The color rendering index CRI> = 80 (Q / naturalness of colors) is also correct
Negatives:
- The actual number of lumens is my (single) lamp instead of 560lm, only about 380lm. This is almost 1/3 less than the specified 'brightness' and thus not really a big hit ...

Who does not bother that the lamp - in brightness - well below a classic 40W bulb (~ 470lm) and even more clearly below the specified value, which is this lamp highly recommended, since they otherwise a bit fancier (eg pleasant lighting ).
Displayed 50000 sins lamp life I have on the fly just can not check ;-), only time will tell but ...