Hi dmn23,
From my reading, Denon i.Link(I think that is what it is call) is proprietary and works with Denon products only. Pioneer VSX-56 firewire is not proprietary and will work with other firewire products.

I was looking at the Pioneer VSX-56 because it has firewire. The HK 7300, their flagship model, does not have firewire, and Yamaha RXV2500 does not have firewire.

You can get the Pioneer for about $1000 if you buy from an unauthorize online dealer.

It's because of this that I'm having a hard time deciding. I want the best audio I can get and seems like I need to get firewire in order to do this without spending more than $1500 for a receiver from an unauthorize online dealer.