The reason I would not recommend the SB is because it is not reliable. In the real world, that's a deal breaker for me.
		
		
	 
I'm starting to wonder about this.  I had one issue early on with a corrupt driver, but aside from that my unit has been rock solid and stable.  I'm sure I'm jinxing myself, but it's been over 2 weeks since I've had ANY issues [and that issue was the aforementioned corrupt driver]
It's been running SO well, I left my 2015 Blade AT HOME for my latest business trip [2 weeks all expenses paid in exile in the Inland Empire], and the SB is essentially my SOLE form of entertainment: my alarm clock, my communications hub, my spreadsheet editor, my gaming console, my journal pad. . . . 
About the only thing I can think of that I may do different is I SHUT IT DOWN in the morning when I go to work.  Sleep/hibernate is still a known and unfixed issue, so I don't tempt fate, but that's about IT. 
The only reason I bring all this up is specifically BECAUSE mine's been so stable.  It's a HECK of a lot more comfortable to work on with the additional vertical real estate, and while it doesn't push Diablo 3 at full resolution at max settings like the Blade does, it ALSO doesn't keep the CPU hovering in the 95c range EITHER. 
All in all, I've had a great experience with my SB.  Is it worth it over the SP4?  ABSOLUTELY. 
No, the real question is:  how will it stack up after all the announcements from CES this week...