Interesting design. I like the way each mower is individually mounted so they can articulate. I actually thought of doing something similar on a smaller scale.
I cut 7 acres with an 84" 3pt mower and it takes close to 3 hours. To shorten that time a bit, I've been thinking of attaching two 26" gas mowers to an SSQA plate. They would be mounted outboard of the 84" mower to increase the cut width to 136". They would articulate with the terrain and could be easily lifted out of the way with the FEL when necessary.
What I really need is a batwing, but they are expensive and are towed, which makes it difficult to maneuver around obstacles.