Bigger Muscles = more water, more glycogen:439: LOL, but I see where you were going with the question.
I myself went from a 3x10 training routine to a 5x5 hybrid and ive had awesome gains, possibly due to changing the stimulus, possibly due to heavy squats and deads and the effects they have on GH output.... But also a while back i came across an old article (from Arnolds day) discussing how a 4-6 rep range is best for both hypertrophy and strength. Now I know science is constantly evolving, but something to think about.
Also i have noticed that my muslce are much harder and fuller looking than when doing a higher rep range.