I agree with your hesitation if you've done zero xcode 3 development. I just completed my first xcode 4 based project last night, and the instructions on Apple'

I agree with your hesitation if you've done zero xcode 3 development. I just completed my first xcode 4 based project last night, and the instructions on Apple's site (for binary signing, and the like) have yet to be updated for xcode 4 - since the process is already complicated enough, had I not done it before with xcode 3 I would have been completely out to lunch. With that said, if you're comfortable with xcode 3, you shouldn't have a problem switching to xcode 4.