The initial decoder file created in 2005 was set as per Digitrax documentation (0=slowest / 7=fastest).
This was changed in 2008/2009 by Matt Harris. The version comments in the decoder file do not specifically explain this change.
@Matt (I think that you are still around) : do you remember the reason for this change ?
@Brian : do you have the possibility to make some tests with your own set up by temporary changing the values?
Alain LM