I sometimes use STL files to export to rendering packages. In this case, low chord heights generate the best renders. The basic tradeoff you are making is:
Low Chord height (more detail) = Large File size (slower processing time as well)
I've been a Pro/E user since '94 and used to work for a rapid prototyping company. In the early days, the chord height was important as it decides the resolution of the file and therefore the part produced - for instance, a big chord height may produce a circle which is more like a hexagon. On the other hand a small chord height would produce a very large file which due to the speed of computers and e-mail connections back then could cause problems. Now, I always put 0 in the chord height box, hit enter and Pro/E automatically changes it to the smallest allowable value. If a big file results - so what?! What is though of as a big file now is a lot different from back in '94. Obviously, if you have a very large, complicated part you could still produce a very large file by doing this and may want to play around with the value to get something more manageable.
Angle control, almost without exception, I leave alone. If you get an error creating the file it is worth changing this and trying again to see if this helps.
