OK, it's finally settled...
Went back in today, because they were supposed to have a SP4 i7/16/256 with my name on it. However, after lots of soul-searching, I determined that an XPS 13 was a better fit for me. While the tablet stuff is cool, I can still effectively do much of that with the XPS13. It's small, light, and I got the one with a touch display. at the end of the day, for this specific system, I guess I am more notebook-first.
I again compared the three units: SP4, SB, and XPS 13, with the XPS just being much more practical for me. SP4 cover KB was nice, but the XPS is better. And though it might not seem like much, that extra inch of screen makes a difference. As a bonus, I get USB-C/TB3, which is where I want to start investing in peripherals and such. Plus, I can share a charger with my rMB, when traveling!!!