I looked at the Dell XPS8700 when I was going to upgrade.  I'm very familiar with Dell as I worked their users forum for over 10 years and attained "expert" status on the forum.  But, it didn't meet what I wanted and had very little expansion capabilities.  I wound up building my own with what I wanted for about the same price.  I don't have any (real) vendor customer support but with Dell's "off shore" tech support, that was a major issue with users seeking help on the forums, who needs that.