This is what one gets for asking: Totally opposing views.
The XPS2 is definitely better made than any of the Sagers. Most of the internals are similar or identical (screens, etc). It might not look it, but the XPS case is much more solid. I'd definitely prefer to have an XPS2 over a Sager of any sort. The same does not go for some of the other Dells. Mind you, I'd also prefer to have the good sager keyboard in an XPS.
That said, I'm about to order a 5720 Sagar primarily because it gives me the same features plus a couple and I can get it for a fair bit less than what it costs to bring in an XPS. I can't say I like the cheap plasticky look of the 5720 though... yechh... I'll just bite my lip and grin

Valuewise: Better value for me cos I can't use a coupon.
Performancewise: Should be indentical seeing as it has identical parts in it... though somewhere I read that the battery life is less in the 5720... might be smaller/cheaper battery.