Cubase Sx On An New 12" G4 Powerbook?, How well would it run? Options

[Sonicom]

Has anyone done any testing of how well Cubase SX runs on a new OS X -based 12" PowerBook G4 867mhz? RAM variations, Superdrive, ComboDrive, amount of tracks, Soft-synths, etc? I intend to intall the maximum amount of RAM that it will take. I will probably be running an M-Audio Firewire interface with it, or maybe an Ozone controller. Any input as to how well this works prior to me making the final decision? Or should I lean toward the 15" Titanium? Will the absense of an L3 cache on the 12" model really affect performance? Portability is a factor, as is price. Then again, so is speed. Any testemonials from the field would be appreciated. Thanks in advance...