Firewire Cardbus On A Powerbook G4, Performance issues Options

[kassotis]

Hi,

I have an external firewire 400 hard drive and the rme fireface 800 audio unit.
I was thinking that it would be much better to use a cardbus on the pcmcia slot of the powerbook and not use the same firewire bus for both the audio unit and the drive.
However I'm not sure whether the powerbook makes full use of both at the same time or it somehow shares them. I guess something like irq sharing...
I'm not very good at that so any info will be great.
I'm also using USB 2 hard drive and some other usb 1 devices so virtually every port of the powerbook is used.
Will it change the performance if i seperate the 2 firewire devices or it will just create more sharing issues...?

thanks

Ion