I've owned the combination of the Zen NX with Notmad for the last three months. Unfortunately, I haven't used the Zen with any of the creative software that was supplied with the player, so I can't really compare.
THe only comment I can make about battery life is it can go south really fast if it's hooked up to the computer while you are transferring or playing music from the Zen. I have no complaints about transfer speed with USB 2.0 using Notmad, but haven't used the webserver feature because it's not something I would use. The ability to shuffle all playlists in the software probably gives you a few hours extra on battery life as the hard drive on the Zen doesn't have to do that under it's own power and shuffling is known for using power.
The playlist backup to your hard drive is a nice feature as it only takes up a a few K's of space and therefore you can add and remove the playlists you have on the unit without too much fuss and time.
Bottom line is you won't be disappointed with Notmad if you already have it or are thinking about getting it. Creative came out with their own drag and drop explorer version, but it's rather featureless. It's been a no brainer for me using this software and after ease of use and convenience, I wouldn't be a happy camper if I had to go to mediasource. I remember originally installing mediasource, looking at it, saying screw that, and then uninstalling it so stick with Notmad and you won't have any regrets, but you will need your own MP3 ripper and burning software as it's not a part of Notmad.
LTM