A friend loaned me his ISM saddle so I could try it. Didn't even use any bibs to test it, just normal clothing, but based on 5min of riding damn is it comfortable to hold an aero tuck all of the sudden. With the big cutout for your soft tissue, it basically eliminates any discomfort you could have and puts your hips in a really forward position at the same time. With the hip rotation, I all of the sudden would need a 3-4cm longer stem to be comfortable and not cramped. I might need to try this out some more, if it's comfortable for longer stretches and I can put out good power then this would really prove useful for racing, especially the flatter ones.
Pic related for reference, I am not even trying to hold an aero position, just what comes naturally after the saddle rotates my hips like that.