Upload & Sell: On
I'm a little late to the party here, and despite my usually running away from threads like this I'm going to add a comment anyway. It also looks like you've made a decision so I suppose it's only for some future reference.
It continually amazes me to see the opinions of this topic here and at almost every other site. I think that many who insist there is only one solution have some, but maybe limited experience with a lot of variety in hardware. I especially love the Dell bashers and Apple bigots...those comments are usually the most closed minded and often misstated of all. Statistically Dell has one of the highest reliability rates in the industry. The record is very good. In fact, in most credible studies all of the major players are surprisingly close. Dell, HP, Lenovo and Apple are competing for fractions of a percentage point. Why do I say all of this? I suppose if nothing else it would be to encourage people to look all around. I get that you have had a terrible experience with XXX OEM, and that really sucks. We all appreciate learning from those experiences.
For what it's worth I work daily with a variety of systems. Currently a couple different Macbooks and a couple different Windows machines. If I were to compare similar configurations I can't say one is vastly superior over the other; they are just different. For me I've enjoyed spending more time with the MBP lineup than I might have in the past.
To that end, I've long been a fan of the Dell Precision machines and the power/certifications and capabilities they bring. Again, I'm not saying it's better than a MBP 15" Retina machine (which really is an incredibly bit of technology) or any other. I think the Dell Precision 3800 is worth a look. QHD display, lots of memory, SSD, etc. Here is a link to a (Dell published) whitepaper comparing to a MBP. Take it not as gospel but rather a point of consideration: http://i.dell.com/sites/doccontent/shared-content/data-sheets/en/Documents/Precision_M3800_MacBook_Pro_1113.pdf
The Asus machines mentioned are also pretty nice too. But in my opinion, a 17" portable just gets a bit difficult to deal with. I want portable, not luggable. I had enough of that way-back-when.
Enjoy the new custom config you are having built!
EDIT: One more quick thing...while the gap is probably closing, there really is a different between what I'd consider consumer-grade machines and commercial-grade offerings. In loose terms, if I can find it easily in Best Buy or other superstore, it is very likely a consumer grade product. The commercial grade products will frequently offer a higher quality set of components and meet many standards quite well. The trade-off might be that they are not on the bleeding edge of what's available. They are designed for stability not the fastest component of the week.