My only thought is a bit about balance, I mean the nose can help you grip to the bike better with the thighs than trying to do it to the frame with the legs, specially for someone just learning to ride a bike (this seat will be for my wife).
Any other thought you have about that kind of seats?
That looks like some seat someone is trying to make up a purpose for. No serious cyclist is putting that on their bike. First time you need to slam your brakes on, you are going to nad yourself on the top tube.
I have never tried (nor even seen except on a tricycle once) this type of saddle, but I feel like if 99.9% of saddles have a nose, it must be for a reason.
I feel like I'd definitely be sketched out on a saddle without a nose.
I have a friend who uses a saddle like that on his bike because he has to sit in a very upright position due to his physiology. It works for him and it's very comfortable but I doubt it would work well in a typical riding position on long journeys.
I use a Spongy Wonder seat. The Spongy Wonder is designed to only contact the sits bones. You are right about to be concerned about balance. When switching from a nose to a nose-less seat the transition is jarring. It takes a little while to compensate for the new saddle and shift in center of gravity. I was back to full confidence in riding the bike within an hour.
For someone learning to ride I imagine it wouldn't be any harder to learn than a saddle with a nose.
The other thing about the Spongy Wonder is that it helps with getting back on a bike if you have any pains or issues in the mid-line since there is no pressure there like a traditional seat.