Every report I've seen from owners of the 15 says that even the 1080 version struggles to get 6 hours so where did you get 17 hours from?
I get about 8 hours on my 2 year old 15 rMBP with Safari. Less than 4 hours with Chrome.
Between Chrome and Photoshop my GPU seems to be on pretty much all the time on my MBP. I get probably 5-6 hours on it working unplugged(my power cable is usually at my standing desk and some days I'm lazier than normal so I get close to this before standing up again).
I get close to 8 hours with a late 2013 MBPr 15".
I don't see any 32Gig update, either as standard (16GB) or even as a customization option.
http://www.dell.com/us/business/p/xps-15-9550-laptop/pd
As for the battery life, LaptopMag gives: 10:26 for the 1080p XPS 15 and a meagre 6:36 for the 4K screen.
I also think the SSD is quite slower, single thunderbolt port (it has 2 USB 3 ports and HDMI), and the touchpad is worse. So there's also that.
Also, dell battery life is only decent with the 1080p screen. Everything I heard about the higher resolution touch screen is that it eats battery life (and the 16 GB of RAM on the XPS 13 only comes with the touch screen).
Yes, the new MBP wasn't all we could have hoped for, but I had held out for a very long time and it's the best option I have.
EDIT: A actually do also have an XPS 15 w/Ubuntu, but that combination isn't quite a replacement for an MBP.
Off the top of my head:
Dell XPS 15 has up to 17 hours of battery life, a 4k screen (that can be upgraded to a touchscreen), dedicated Nvidia GPU and up to 32 gigs of Ram
The Razor Blade and perpetually on the horizon Razor Blade Pro have QHD or better touchscreens, 16 gigs or more of RAM, and the best line up of dedicated graphics cards you're going to find in a laptop. Oh, and they did reactive/programable touch keyboards without removing core functionality from the device. Can't find specs on battery life at the moment. Plus, mechanical keyboard and glowy lights!
And there's the ThinkPad line up which has basically everything under the sun now.
Not to mention the Surface Book, which claims 12 hours of battery life, meets your dedicated GPU and RAM needs, and has a killer scree, that supports a some rather interesting input devices. And it can connect to an iPhone 7 without a dongle.
There are options out there.