The concept behind the above is very simple, the bot just places a back bet on under 2.5 and greens up for a small profit, currently 8p on 40p liab.............even if there is an early goal it can still come back to profit if there is not another goal soon after. I have interfered with it a bit today (hence P/L's dont reflect 8p and 40p). because original back bets were not being matched (I was probably asking too high price). I then tried offsetting with greening, instead of green up rule, placing pre-off with "keep"............that did not always work 'cause sometimes my bet was matched exactly at kick off, so the offset was not placed, or the original bet was not matched pre-off and it was taken inplay..............and with an early goal, my "keep" back bet of asking for 2.1 was soon gobbled up as the back price went to 4 after the goal, so I interefered !
I will be interested to know how your strategy gets on with the bot I posted, when I was testing it the only matches it was "green" on were half time 0-0, so I wondered if just backing 0-0 half time score would be easier! but I was testing it on any and every match I could find, and you have probably been more selective on your previous manual strategy testing.
I have just looked at my P/L again on the 40p bot, its down to £0.95, two consective losses of 40p did not help.........I think they were two matches that did not go inplay, something else to look into and iron out. Happy days though, betfair have just given me a free £5 bet

for being a loyal loser, er, sorry I meant cusotmer!
Good luck!