Syncing two libraries

I'm on a quest..

A quest for the ultimate iTunes syncing program between my 2 Macs.
I've got a iMac with a big HD, and a PowerBook with a smaller HD, so it should only contain certain songs or genres

I found the following two already:
Synctunes
Let's you select certain playlists, but only copies them to an external device, it doesn't update the iTunes library itself

SyncOTunes
Updates (and compares) if needed 2 iTunes libraries, but doesn't let you choose a specific playlist.

Does anyone know a program that let's me:
SELECT a certain playlist on my iMac (which contains my entire music collection)
COPY the songs in that playlist to the PowerBook
UPDATE the iTunes library accordingly.

At the moment I'm updating the PowerBook's iTunes manually (by copying the files over my network) , but if I could let a program sync the two libraries or specific playlists, all newly added items, future changes in albumart or mp3 tags etc, would appear on both devices, and would give me a LOT more free time.