Dual Port 10GbE Server Adapter question

[Brian Proteau]

I'm trying to understand these a bit more. I'll probably end up getting one of the models below but, I'm wondering if I can fully utilize both ports.

(1) Is it truly pushing 10GbE from each interface?

(2) I'm not clear on server PCI slot implications with dual ports. Are there any server bus saturation implications with this much throughput through one PCI Express slot? These will go into Proliant DL380 G7 servers.

These are the 2 I'm looking at. Besides some manufacturing differences, I'm not seeing much functional differences between the 2. If anyone has a reason to choose one or the other, please advise.

HP NC550SFP Dual Port 10GbE Server Adapter
HP NC522SFP Dual Port 10GbE Server Adapter