Won't the database size be dependent on RAM?
There is some uncertainty on this issue, at least on the forums I visit. AFAIK no Creative employee has definitively answered this as of now. As far as Creative is concerned there is no problem, because they didn't market the Zen to be user storage-upgradeable. A lot of us early purchasers are hoping the problem can be resolved in software, but no one is sure.
The Ipod and (I think) Perl use 1.8" HDD vs 2.5". I haven't heard of anyone who has upgraded the disk in an Ipod. I suspect it's a quantum leap more difficult than the Empeg or Zen. And there's little to be gained in doing an upgrade, since 30GB is the biggest 1.8" HDD model IIRC.