But in the long term (years) they should just about equal out.
Just FYI, to equal out over the course of years, you would need a decent amount of speed (50 GH/s+ right now) that continues to grow proportional to overall network speed. Otherwise, you're looking at a time frame of decades/centuries or more :p. Right now, 50 GH/s on average won't even find a block per month, meaning you'll on average see 2-3 difficulty changes between solves. A bad luck round is normally 3-5x expected time frame, which at 50 GH/s [and upgrading each difficulty increase] would be 5-9 months. Extremely bad luck rounds (which do happen) are up to 10x difficulty (and very rarely, even worse).
It would likely take you years to recover from that bad round, assuming you continue to increase your hash rate proportional to the network difficulty the entire time. The flip side is, you could end up _way_ ahead with some good luck rounds early on.
