I have been working on this to establish any profitable methods using the bottom end of the ratings. Would it appear to offer a laying opportunity although the first month it is a profitable backing option? Or is it too variable in being a blind winning/losing season-long play? Only one way to know for sure.
bottom rated 69/746 -70.72pt betfair SP after 5% deduction, SP -179.11pts industry SP
Bottom rated -40 54/616 -100.97pts betfair SP after 5% deduction, -165.37pts industry SP
potential -40 system 35/335 +23.46pts betfair SP after 5% deduction, -31.75pts industry SP. This was different from the NH version in that this is 7-16 runners, max 9f distance, max OR 85, and for bottom rated -40 only.
Figures a little out of alignment due to some races only having the top 6 rated