I have to point out one thing since Professor Monkish may not be available at the moment....percentage is percentage regardless of PPS. Now, granted it only takes .10 move to make a better $ return on a 4.00 stock than on a $40.00 stock, but that $40.00 stock may be a lot more volatile and move the percentage you need faster/more predictably/"safer"/etc.
It's all about the percentage...and a combination of the other things.
Mama and Daddy always said it's how you play the game - trade to trade well and the rest will fall into place ;-)