Dave insists that the coupe was a full in house design, but it's hard not to see a lot of similarity between what they are building and Vman's photoshop job. Yes, they did design this in house, but I think they took some inspiration from Vman. FFR jumpstarted the 818 with a design contest and set up this forum for a reason. It's clear that FFR reads the forum and listens to what people like. Dave obviously values the input from their customers and fans. The biggest difference I see, is that FFR is putting in a small window in the rear quarter panel, where Vman shows it solid. That window, I think is a big improvement. Other wise, you have a substantial blindspot. FFR is also using the same scoop on the bottom of the b-pillar that Vman shows, which I think, will look pretty cool and may prove very useful.
The big rear window, however, I'm personally not a fan of. Having glass over your engine might look cool at the car show, but I'd rather keep the sun off of my engine, especially since horizontal glass traps so much solar heat. I think a small vertical rear window like on this Corvette would be much better:
corvette-036-2.jpg
Alternately, they could keep the current design, which is more aerodynamic, but for buyers who don't want the horizontal glass, add one more option. It could be shipped with the rear glass or the window behind the seats. Instead, it could be shipped with a solid fire wall panel to go behind the seats. To replace the glass, it could have a lighter-weight, fiberglass panel, either solid or possibly with vents, like this:
Venom GT roof.JPG
This would allow the roof scoop duct to go straight down rather than snake to the side. IMO, rearview mirrors are overrated. With such a sloping roof line, you can angle your side mirrors to see who's behind you.