well, the 'puter in my Mazda puts me at ~ 70 mpg when coasting in neutral at 20 mph, and something similar when in gear. At 65 mph that would put me at over 200 mpg for neutral(the 'puter goes offscale at 99mpg). If I was driving over mountain passes each day it might be worth it to figure out which is more efficient, but for normal commuting the difference in fuel consumption will be negligable. It's all burned while accelerating/maintaining speed, not while coasting and braking. If I coast for 2 miles a day in neutral at an average of 100mpg, vs the engine burning NO gas at all for those same miles it would save me all of 7 gallons a year. A new clutch will cost me close to a grand, putting extra wear on it to save 20 or 40 dollars a year is penny wise/pound foolish. For braking moderately I let the engine brake the car til the rpms get low, then just take it out of gear.
I'm not sure about shifting at lower RPMs either. It means shifting well below the torque peak when your engine is not at its most efficient for accelerating. You end up having to put your foot down further to accelerate at all, and then you have to keep it there longer to get up to speed. The 'puter says I do better when I use a lighter foot and stay in a lower gear a bit longer, shifting in the high 2000's rather than the low 2000's (2.3l 4 cyl, 5sp manual). It might be more applicable if you're driving 6+cylinders.