I'm currently running a 12-27 SRAM cassette with 39/53 chainrings.
I know that most front chainrings for CX are in the range of 38/48, so I suppose I'm fine with a 39 as I doubt I'll ever need to shift up as a beginner.
So that brings me back to the rear.
I just finished a custom set of gears to maximize my wife's new bike for road use as a beginner.
13-30 is what I created with 2 tooth steps the first set of gears and wider for the last set.

So I'm now thinking of using the remaining cogs to make up a cassette for some CX use.

Would going to 30 tooth be worthwhile? Or does dismounting negate the need for granny gearing?