As noted here, Dell is no longer allowing 3rd party disks to be used with their latest servers. As in, they don't work period. Which means that if you buy one of these boxes and want to upgrade the storage later, you have buy disks from Dell at significant premiums.
Dell has just given me a very strong reason to take my server business elsewhere. My company buys (instead of leasing) our servers, and typically uses them for 5 years. I need to be able to upgrade/repurpose storage periodically, and do not want to be locked in to whatever Dell might have in stock, at inflated prices to boot. As you will see in the comments of the above link, it seems HP is doing the same thing.
I am looking for a server vendor that offers 3-5 year warranty with same day/next day onsite service, and allows me to use 3rd party disks.