Firewire Options On New Imacs, Is the 400/800 combination significantly better? Options

[cgt18]

I'm looking to buy either the latest 20" iMac or the 24" model.

I think the 20" screen size would be enough for me but I am wondering if the 2 x Firewire 400 ports will be
ok....or to look at it another way would the 1 x 400/ 1 x 800 on the 24" model give me a significant performance boost. I would probably go for 2 Gig of RAM to begin with whichever machine I opt to go for.

I am running Logic Pro 7/ Motu 828 MK2/ Powercore Firewire and a LaCie external drive via Firewire for my
audio files. Current computer is a 1 Ghz/17" Powerbook /1 Gb RAM ( I use the 400 port for my Motu, the
800 for the Audio/HD and the Powercore goes into the 2nd Firewire port on the 828...)

I rarely go to more than 24 audio tracks on any song.

Any thoughts much appreciated!