The 422 control ‘s always better than firewire. Wich codec do you use? It sounds to me, that your system’s not fast enough. Another problem could be a sync signal, but if you use firewire dirctly it seems not likely to me. Do you have timecode gaps between clips?
If the sound is low try high pass, if its high try low pass. If this doesn’t work, you have to go with the sound as it is. Then the sound goes over several frequencies, you never get them out without loosing the frequencies in you voices.
I did a Projekt withe the la cie bigger disk raid on 800 FW on DVCPro codec. Everything wnet smooth. You need the SCSI or optical fibre for 10 bit uncompressed or HD. As long you just be on DV up to DVCPRO 50, the raid with FW 800 is fine.
I think the problem will be solved when the 200 is out. At the moment you import the P2 data either through the camera and USB or you have a p2 card reader which is 2500 quit (a hell of a lot of money for a card reader) The import of the P2 data in FCP works excellent.