Best NAS... To Firewire or Not?

OK
Looking at going with a NAS to hold my muscic for my Sonos.

I am going to use it to store all my music and have ITunes draw off there as well. (yes ITunes isn't the best but it works for what I want and I will not use ITunes to burn)

I have looked at the:

Synology DS411 Slim and its a nice system, pretty hands free after set up which is a bonus for me but I figure I might as well get something with Firewire support since I run a Mac?

Also looked at READYNAS NV+ v2 but same thing, USB.

Is there anything nice, easy with Firewire or should I just forget firewire?

I was also going to go with the Rega DAC but again that is USB so I may change that.