OK, the holdfast is not hand-carved, but is cut by the machine. But it's the holdfast that is sewn through (yes, backed by a canvas strip), by hand, and acts as the main rib holding the insole to the other parts. Even though it is reinforced by a canvas strip, I don't think it's correct to call this gemming in this case. The video states that the insole leathers are 5 mm at the end of preparation before being cut. For shoes costing around 650-700 euros their techniques seem to be laudable, no ?
Yes and no. The leather rib is indeed a kind of holdfast. The canvas reinforcing is gemming, nothing else.
The real issue here is, as I mentioned before--you're forcing the the leather fibers into a position that is perpendicular to the way they would naturally want to lay.
First they are cut, then jimmied vertical. Just doing that, creates a strain on those fibers that is not natural. Then you "postage stamp" the rib.
What I've seen throughout the years is that the rib breaks. When the rib breaks it's almost worse that a simple slippage of the gemming in the more common cement gemmed shoe, because when the gemming slips the insole remains full thickness. But when the ribbing breaks the best scenario is that there is a portion of the insole that is now roughly half the thickness of the rest of the insole--creating a depression under foot; And the worst scenario is that when the rib breaks it takes some of the leather at the base of the rib with it.--creating an actual hole in the insole.
Without that thick slab of cork the rib breaks even sooner simply from the weight of the body as well as the force of the shoe flexing. Take a wire clothes hanger and bend it in one place. Now bend it back and forth in same place ten to fifteen times. What happens? The wire breaks. The same sort of stresses and forces apply to this kind of construction.
Having said that, I do believe that this variant of GY is significantly superior to GY that relies solely on cemented gemming. But it can't hold a candle to hand welted.
On a scale of one to ten, with cemented gemming being one and good handwelted being ten, leather ribbed GY would be about a four in my book....maybe a six if the leather is really well tanned, supple, long fibered, and heavy enough.