I can't answer for Tim, but in my case the 30T chainring with the 36T cassette cog gets used frequently on the types of dirt stuff you describe. I also find I need one or two gears lower for my WTB nanos than for my road tires when climbing the same (paved) hill. I've used the 30/36 combo on-road, and it made climbing 15 to 18% grades significantly easier (not that it is ever easy).