If you're at the point where you're in the 30-25 and you can't keep the cadence up, that extra 2 teeth will seem very worth it. I run a compact (50-34) with a 12-27 cassette. Although I can ride the hills in my area with the 34-25, there are places where my cadence would drop too low for sustained periods of time and this would often aggravate my knee. Adding 2 teeth wasn't very "manly", but it was worth it.

Bob