FibreJet read/write access

We are thinking of purchasing the Fibrejet to hook 2 G5's up to our Xserve Raid through a Qlogic switch. I just had a thought that might be bad. I'm looking through FibreJet's manual and not seeing it yet, but i understand that only one system is able to get write access at a time. Is rendering, creating titles/graphics, copying files to and just basic editing considered writing? For some reason we were just thinking that digitizing video would be fine for having one person do at one time but wasn't sure about the normal things you do while editing a spot.

I have been advised not to split the Xserve Raid into two seperate Raid5 channels since we are starting to do some HD spots and all the drives need to be populated and read across for optimum bandwidth in a Raid50.

Also, Floh had mentioned that we need a USB Dongle. What is that for exactly?

Is it just recommended that we have two XserveRaids, one for each mac? Is there another solution without purchasing another one and keeping the Raid as one volume?

Thx.