The 500 limit is very common for displying old(saved) tracks on the display. The etrax can only show 500 track points for previous tracks, but can display more for the current track.
The way I use my gps is go to a riding area, turn on the track I have of that area, and now I can see all the trails in the area, plus my current breadcrumb trail.
Ok that is different then... it is common for older units to "filter" or reduce the size of the track when you save it. So, a 3000 point track becomes 250 or 300 points when the unit archives it.
What I was referring to was the "active" or "current" track, or as you mention your breadcrumb trail. 500 points maximum for the active track would be totally useless...