Great video. This should serve as a template for how all "side by sides" should be done - really nice work.
I own both of these instruments in a similar serial range. In fact, the VII was my first "pro" horn back in my freshman year of high school. To my ears, the VII is bigger, more centered, and has a more even timbre through the full range of the horn. The VI, on the other hand, does that magical VI thing where the bottom end can be smokey, dark, and subtone-y, but as one ascends the tone becomes brighter until it really sizzles in the palm keys. I will say, however, that this VI, like my 98xxx, seems to thin out a bit at A2 and above.
Based on this video, I, as a listener, prefer the VII(!). However, as a player with small/medium hands, the VII is too much of an adjustment for me keywork-wise (especially the LH pinky table), whereas the VI fits like a glove.
Thanks for a great video.