I have seen a noticeable difference between 4.6 Medium (the default, and I skipped 4.7 because of various reported issues) and 4.8 High or whatever the default is now. It's far more likely to say it doesn't know and seems to think about things a lot more, but then it also spends a lot more time reporting on what it's thought about so it takes longer for you to process the output. In particular 4.6 would say "I've spotted something a bit off here" whereas 4.8 will say "if you do this and then this and then this under these conditions then something will go wrong here". So it seems to be closer to the claimed capabilities for Mythos than previous versions.