If I could edit my original post (better nettiquete?), I would change that I am going to use MPIO instead of 802.3ad since XenServer supports it, although it is not the easiest thing in the world to configure, I'd like the additional throughput (400MBits/sec theoretical max vs. 100MBits/sec).
I don't want to discuss MPIO vs. 802.3ad, just if I should change anything / add anything hardware side before I begin to think about deploying this server to a production SAN.