I agree it is more difficult with having to take the extra step of keeping up with the rates and sending in the form. The savings are real though for those that want to take the risk and keep up with the rates. The earlier you book the more you save. The early saver rate I have locked in is currently beating the past guest rate by $300 and the current early saver by $200. I booked in January though, and they didn't have the past guest rate available at that time to compare.
I usually book the past guest or resident rate if available and get the adjustments as long as they will give them to me.