What is it about the SYM UI that you don't like?

I can say that what I do like is the flexible screen configurability and the efficient way you can perform common actions such as task setting, task changing, checking the details of waypoints or airspace and zooming.

I run an Oudie IGC alongside my LX9000 and consider it the gold standard in portable glide computing.

In both cases I know the software very well. I completely agree that the critical factor in flight software is familiarity.