I put my Jukebox 3 on top of the keyboard a lot and it always works flawlessly. I record myself almost every night, using the internal battery. No need to take a power adapter. It will RECORD up to 6 or 7 hours. No telling how long it would play. And I don't even have the optional second battery. It records in your choice of several WAV or MP3 formats, and easily transfers to computer via the free program and USB. You can organize play lists easily.
I recharge the batteries in my car as I listen to the recordings on the way home. It also comes with AC Adapter/charger.
The Zen will most likely do everything you want, but it doesn't record.
Creative has wonderful customer support and issues software upgrades periodically. They are still supporting the orginal Jukebox 1, which has to be 5 years old by now.
DonM