Did an experiment flatbetting. Wasn't so bad. +570 in 500 live spins.
I played first with 6 hot numbers, then 7, then 8. For the last 150 spins or so I played with 9 hotnumbers.
Take a look at Mr J's 8 Train when you get a chance...less hot numbers works better for alot of us...something for you to consider when you start working on long-term tweaks....good starting and ending point. There are likley a considerable amount of methods very similar...everybody has their own preferences on the amount of inside numbers to play.