One of the things I've seen is to have the zoom level on the Edge 500 set to say 120m or greater
Do you know how to set the zoom level on the 500?
I've noticed the scale adjusting according to how far the virtual partner is ahead or behind... that slows down the display, and as it is continually adjusting it is hard to tell what you are looking at.
I recently asked Garmin if it was possible to turn of the virtual partner (a useless feature!) and the answer is "No."
BTW. I have found the turn-by-turn instructions to be both beneficial and reliable. I use bikehike, and while entering the turns is tedious, especially on long rides, it does pay. I stick the turns exactly on the corners and then add 150m when saving the file.
If 150m sounds like a lot - it isn't when bombing down a hill! Of course it is a compromise - in towns one instruction may come on top of another - I handle this by combining them in a text, eg. "bR L" (the same means as for entering "info"). Incidentally, those texts do not have the 150m added, so have to be adjusted to a position ahead of the junction - that is a shame as (more important than choosing >=< 150m), you want consistency so you have a good idea what to expect on the road, ie. do I turn at this junction or the next (a weak point of having no maps).
The coolest feature about the instructions is the GPS will light up at night (for about 10 secs) - so you not only get to read the instruction, but also be reassured you are on course and your GPS has not died!