Going to a 30T chainring from a 28 would make it 7% harder to climb. The longer the hill, The greater overall effort required. The short hills where I live I can climb with tall gears. If I had to climb a moderately steep hill 1/4 mile long I would need a much lower gear.
On the plus side though it will pay off under light loads. Sometimes it ballances out. A little more effort to climb is rewarded with more efficient riding at other times.