I race at CRC raceway and they do bump ups. The cool thing is that they run three classes (spec, stock and pro stock) and that the winner of the A main in one of the slower classes gets to bump up to the lowest main of the next faster class (spec A winner bumps to stock, stock A winner bumps to pro stock). This is all 1/12 on road btw.
I have found that getting to run against (ok, get beat into a pulp by) the pro stock guys really makes you push hard and figure out were you need to pick up speed.