Much Ensemble Music is written as a set of single "lines".
This means that a particular line may well be playable in more than one position on the guitar.
The first position (and in particular the top string) is a harsh position in which it's not possible to do vibrato.
Quite often, my free music and my published music can be played in a higher position. The shorter string length and the thicker string combine to give a much improved tone, and the ability to add vibrato can create the illusion of extra sustain.
Just because my music doesn't require you to move up the neck, doesn't mean that you mustn't !
Try refingering my free music in positions V or VII and see what I mean about the tone!