Ok, did a few tests during the weekend. The test firmware performed very well and there is a noticely improvement in terms of micostutters. Mostly they are gone. Playback of 29,976 content is very smooth.Good work!
Test setup: Samba Linux Server->Network->Himedia Q5 ->Hdmi-> Receiver Pioneer VSX- 924->Hdmi-> Beamer Optoma HD25e
Unfortunately, playback of 3D blueray isos seems to be broken. 1080p24 framepacked video is replayed as 720p60. Therefore the aspect ratio and resolution is wrong.
Audio is asynchron, too. Audio is drifting away and the drift increases during replay.(Audio is always outputed earlier than video).
The audio sync issue was also observed with the official firmware 1.8.0
Normal blueray isos worked as expected.