I bought a d40 this summer, i have run into the pictures of nothing with wind sometimes, but the battery life is really good so not too many worries. as far as wake up time it takes pictures quickly when it's on, but i believe that the camera goes into hibernation when not sensing anything to save batteries, so it might take a little bit to start up before firing off the picture.
That being said i really think that moultrie makes a top of the line product, the picture quality is above average, and you don't have to deal with the black and white and blurriness of the infra-red version (which i also have). You won't be disappointed!