And here I am, just having bought the Tamron 24-70 VC not a year ago...
In all seriousness, if they could make this thing in a not-too-huge package below the $1500 pricepoint, I'd go for it, especially with all the killer lenses sigma's been putting out recently.
I bought one in January and love it. If/when this Sigma comes out and is reviewed I'll strongly consider it. Until then, I am very happy to use the Tamron.
6D, Fuji X-T1, X-E1
Tamron 24-70 2.8 VC, 70-200 f/2.8L IS II, 400mm f/2.8L II, 100mm L IS Macro, Sigma 85mm, & 35mm f/1.4's, Rokinon 14mm f/2.8,
Fuji 23mm 1.4, 35mm 1.4, 56mm 1.2, 14mm 2.8, 18-55, 55-200