Hi Crash,
Perhaps we just have opposing views on this issue.
If a favourite is showing $2.50 on the tote and I rate it as an even money favourite, then I am getting 25% overlay without panicking (and it's quite easy to rate even money without the gods :wink.
And it is a great deal better than a 5% overlay on a $5.00 shot.
Yes you need a higher than 50% strike rate, but you'll find that a with a few filters and effective ratings, this is acheivable without heart in the mouth stuff.
Believe it or not, I get overlays place betting favourites applying strong filters.