Hi Mad!
Just my opinion of course, and you (or anyone else) can try to prove me wrong, but if your strikerate is not good enough and-or your return is also so low, that you have to depend on a marginal difference in prices on offer, then you never really make long term profit.
Sure, sometimes you see quite large differences between TABs, but in the long run it all comes out relatively even, I have been watching it for some time now.
It is far more profitable to improve the strikerate or eliminate low paying nags. On top of that you will save yourself a lot of work and mistakes.
Just a thought.