I have been using my front brake only for braking for the past 2 years and so far no untoward incidents happen. Since I am riding at an average speed of 20km/hr, stopping my bike is not a problem at all. Ever since I learned this technique from the late Sheldon Brown website, I will not have to replace the rear brake pad for a long long time.
I am a fan of V-brake for its low and easy maintenance. My brake pad normally cost me about RM5-10 a pair. I don't use all those expensive brake pads as I just use "Chap Ayam" (ordinary) rims. Commuting bike does not require all those high performance brakes and rims. So start learning the technique of using your front brake and you could save more!