Might be worth registering on http://www.spymac.com the PowerBook range has been due a speed bump for a long time now, and G5 PowerBooks are estimated around the second quarter of this year, so it depends how soon you want a Mac
Yes they are really that reliable. With a laptop you pay a lot for portability, take for example my iMac G5, 1.8ghz processor, 20" screen, 160GB HDD 1GB RAM cost about £1500, You cant even get a PowerBook of the same spec to that, and 15" PowerBooks start at £1,350, and still that spec is no-where near as good as my iMacs. When I bought this iMac I was going to get a new 15" PowerBook, but in the end I sacrificed portability for power.
I would say ask on SpyMac and then see what they say.