That's fine until you take your Pro back to apple and they don't have your configuration available and you have to wait 3 weeks for a replacement (this does happen a lot with non standard apple build to order devices). Even worse with an XServe I inherited: they couldn't replace it in warranty. Ended up with a supermicro 1U with debian on it in under 24 hours from buy to install.

My HP: redundant PSU, disks, next day service for all parts or replacement unit.

No competition. I can't afford the downtime.