Stock C-5.... at least the 09's.... have 12.5 inch shocks. Going longer on a B-5... say a half inch... MAY give more travel, and it MAY slow down the steering as your weight is shifted forward. But it will also shorten your wheel base a tad ... especially under load as the rear wheel and swing arm want to run forward and under the bike.
It works nice for me, considering MY geometry and my riding position. And for the bikes geometry and wheel/tire size. My bike sits slightly taller at the rear, unladen. With a 120/80/18 and a 90/90/19 in the front. With me on it, it sits about dead level , with my weight forward with low bars. Taller bars will lighten the front end some... compressing the rear shock more as more weight is shifted back and the front end becomes lighter. Just an example of what I found on my bike, you may find it different with a B-5......