AFAIK the largest vehicles made with the "UFO" design were of a scale similar to the one in the pictures. IIRC (I did read up on it a while back) the main problem was difficulty with stability and control, so they shelved the plans.

These days, with computer control, reacting to changes in dynamics hundreds of times per second would be perfectly feasible, though, so perhaps those challenges are ready to be taken on.

Some modern aircraft are deliberately designed to be inherently unstable and require constant active control from an onboard computer to remain pointy-end-first. The advantage is that when you do want to change direction, it can be done very quickly indeed. With that and thrust vectoring, you can also make a plane that will function in states where a more traditional design would turn into a billion dollar brick (see Relaxed Stability and Supermanoeuverability)

In terms of scaling it up to larger sizes, I expect they'd scale reasonably to a point, but as you get larger, the sheer volume of air you'd need to huff around starts to be an issue. The density of air doesn't go up as your aircraft size goes up, so it's not just a matter of doing the same thing but bigger.

The article linked to by OP was only talking about using these kinds of techniques for control surfaces, though, not for directly generating lift, so we're only talking about a pretty small fraction of the required oomph compared to the flying saucer.