Mate, I'm placing live bets using my Livin' in the 80's system. With my rules I don't place a bet if SP<$10, as I've found that every now and then in historical trials you can get a horse with a 70-80 rating that starts favourite. In other words local knowledge reveals a smokie that they've been handbraking for awhile. This could happen with your system too as they are very silimilar.
When manually placing a SP bet you have control over your liability, you don't have any control over min odds to prevent getting burnt by a smokie. The only way I can control this is to sit at the computer all day and watch for such an occurrence and not place the bet. You obviously place all your bets beforehand in one hit, are you then confident that your system rules will always throw up a longshot and have no fear of it shortening into favouritism?
The other thing I notice is the rules select sometimes 150:1 shots or greater so you're risking $333 to make $2.20. Do you set a max odds, or just work on small bites high turnover?
Cheers
RP