That's very impressive. The red twigs in the first video look like they're much closer than 9 feet. Now if it focuses OK in dim light and has a stability system as good as Sigma's then you might have a lens as good as your Sigma 150-500mm coastalconn.
The MTF charts indicate the Tamron is going to be sharper and have higher contrast than either the Sigma 50-500mm or the Sigma 150-500mm, except for two strange quirks of the Sigma lenses. Both Sigma lenses appear to have less astigmatism than the Tamron right at the edges of a cropped sensor camera but won't be as sharp closer to the center, at shorter focal lengths. At longer focal lengths that is still true of the 50-500mm, but not for the 150-500mm which is worse than the Tarmron at 600mm all across the sensor with the Sigma showing less contrast, more astigmatism, and less sharpness.
Again though, for those who print large this tilts towards the Tamron, and for those who mostly post to the web the ultimate sharpness is not as important. The extended short focal length range of the Sigma 50-500mm with a shorter minimum focusing distance might well be more signiicant to your work, while the extended long focal length range and higher IQ images might appeal more for what others need.