@aniol:
The only difference i noticed is that, on firmware 2.3.0 the camera does more often recalibrating. Has anyone observed this behavior?
There is no 2.8.0 firmware to download. Also, there is no way back.
Before i did the downgrade, i downloaded all files over ftp 2.8.0. But i don't know, if this would help if i brick my device.