PG wicks faster because it is thinner, this will also effect the amount of vapor produced. When dripping, you don't have to really worry about wick speed of your atomizer/cartomizer. They have to soak the fluid up and move it to the coil. VG is horribly thick when un-diluted, and can burn cartomizers because the fluid moves too slow (wicks slow) and the coil burns.
Yes, VG naturally produces more vapor when dripping, and a few styles of attys. Cartomizers though, especially the CE2R4 variety LOVE thin juices and will produce insane vapor if you can feed them a thin juice fast enough. Simply cutting VG with everclear is my normal route when bored and just want to vape VG and not burn up my attys or cartomizers.