Opinions on my next double build (Second PC added)

[#1]

I also agree with the fast and functional hence the Dell, how good the machine looks will not make it go any faster to me it's the equivalent of a 'go faster stripe' on a car. I use the Dell for mathematical modelling but I also do a bit of this on nVidia GPUs using CUDA so the target is to migrate all possible models to this platform.

[#2]

You don't need a SSD for video editing.
But two disks would be good for video editing.
1TB might be a bit on the small side for video storage.
There are plenty of 2 & 4TB disks out there.

[#3]

On the first box it might be an idea to use Resource Monitor to identify the bottlenecks with your application mix.