I am wundering wether I am the only one who finds it hard to steer on the heading bug?
I never had that problem with the steam gauge but with the Aspen the heading bug is the same colour blue as the rest of the displayed stuff and I tend to find it hard to keep it centered.
I asked Aspen wether they could change that colour but they say it probably was the FAA who decided that colour. I find that hard to believe because the the g500/600 have a purple heading bug that contrast much better against the rest of the display.
I don't have any problems operating the Aspen's heading bug. It's true that the Aspen screen is cramped with information due to the wealth of functionality and the small form factor.
It is not always easy to see where the heading bug is but you have a rather large display of the current heading. When in HDG mode, this is where your heading bug is, when not in HDG mode, you can just turn the heading knob to make the line appear and find the bug. I always do it that way and don't ty to identify where the bug currently is.
When HDG is displayed in blue in the bottom right corner (the standard if the unit has not been manipulated for 10 secs. I think Aspen calls this the home state) you can either twist the right button one click or simply press it to have the heading bug turn magenta and a magenta heading line appears. Also, in the top right hand corner of the HSI the setting of the heading bug appears in a numerical value in magenta. As achimha pointed out, this makes the heading bug a lot easier to identify.
The Aspen has a synching function which I find quite handy. When HDG is displayed in the bottom right corner and one presses the right button for more than one second the heading bug will be set to the current heading. In BARO, pressing the button for more than one second will set the QNH-value to standard.