I began using Dimension before switching to Prodiamine. There are 2 reasons why I will never switch back:
1. Cost - Dimension was $30 for a 25lb bag + $58 shipping to Canada. Prodiamine was $58 + $53 shipping for 5lb but the app rates are much lower, meaning it will last me years and years. I believe I got approx. 6 apps out of my bag of Dimension (2 years worth of apps).
2. Ease of application - As I became more comfortable with spraying, I began to see the benefits over spreading. I get much better coverage with spraying vs. spreading granular.
Someone may say differently, but I don't see a need to rotate between the two products. You can't go wrong with either.