If a horse is $10.00 into $5.00 wouldn't that be somewhat reflected in both the Betfair SP and Top Tote or am I confusing/missing something?

The concept I'm thinking of may seem reasonably trivial but I just figure if there is some way to eek out any additional bit of value in terms of what price i'm achieving then that just adds to the bottom line.

Unfortunately I've only recorded the BetfairSP prices for the 1300 races i've noted down in excel so far with my ratings etc. I've just checked one bookie and they have the top tote results going back some way. Might have to manually grab that and compare over my 1300 races to begin with.