I've been recently surprised at how much weight feet elevated pushups load onto you. I weighed it with my scale and it said 74 or 75 kg, and I weigh 100kg, so that's about 75% of my bodyweight as compared with regular pushups which are 70% of my bodyweight. It seems a paltry increase, but the angle of feet elevated pushups puts and keeps a lot more pressure on everything, so I suspect the benefit is much more than a mere 5% increase in weighted load.