Clevo makes the chassis for many laptop makers. There are only a couple really a couple of OEM laptop case makers before the companies they sell them to slap their own logo and flare on it.
Clevo leads the way for what goes into laptops.
Sager and other smaller brands use base Clevo models with little flare or variation.
The reason why Sager is one of the best, if not THE best laptop maker is they use A++ quality cases and are able to cram a lot of computer into a laptop for a price that will leave you with a little left over for other things.
THe reason why you would purchase a Sager through another retailer like XoticPC is that for one it will be cheaper then ordering through Sager direct, you can customize pretty much every aspect of your hardware configuration, and XoticPC will use quality parts whereas a company like Dell will use cheapo oem parts.
I do not work for these companies believe it or not. I just spent a very large amount of time researching this very subject before I bought a new laptop a couple of months ago. So the information is still fresh in my head, and I feel like passing my knowledge on. And if I can get Sager to pass one more person's tongue then my job is done.