To be honest. I just opened up UE4 and tried to replicate what I saw in the first minute or so of the video (video A) you had posted, and everything he was doing, sliding a corner inwards, pulling it up down, transforming the shape, is exactly how the new tools in UE4 operate, I am not sure what was available in UDK (I used to use CryEngine back before ) but I think you should give the new BSP controls a try (to do so, create a box, whatever size, then in the mode panel go to “Geometry Editing Mode” and all of is possible.
Give it a try! 
Oh and I agree with here, 3ds is definitely the way to go if you have the cash to spare…