I have just had another go at decoding, this time feeding in the signal(SPI) from the competitor's demoboard.
After a few attempts, I managed to get a super-stable signal.
First with 3 channels, so CS included.
I used the "Pulse" trigger.
Then I looked to see if I could do the same with 2 channels and timeout.
Yes, but a few letters were missing, the solution was that the default timeout is 1µs, 8µs was then enough.
Finally I tried it with the SPI trigger.
This also enabled me to create a rockstable trigger with a timeout of 8µs.
Interesting:
In the SPI trigger menu you can only select MISO, but I had previously deactivated MISO in the decoder menu because it is not available on the demo board (only MOSI).
Conclusion:
The decoder signals on the siglentboard are also "bitchy"(like on the batronix board), but with the right settings the DHO achieves super stable decoding - very good.