It would sound the same*, and make the file
smaller. You can also change the instrument
number to do things like change the duty-cycle
of a squarewave without affecting the
frequency, which is great for being able to
do duty-cycle or other instrument changes
during note-slides and such.
*
= Resetting the instrument in that way will
not re-trigger a non-looped arpeggio. It also
will not work if you have the Hold-Note
setting disabled.
You can also save some space
by removing the instrument numbers from the
pattern in the triangle channel. Just make
sure the first note in the pattern has an
instrument set. Since that will not reset the
volume, it won't work on the noise or square
channels if you are using volume effects.