the ETFE is not only naturally a barrier, but will likely also have a UV shield.
it may be slightly warmer than a solid roof, but not much. The larger complaint is that it will always feel like playing in the shade.
The lights will seem brighter on the Jumbotron stuff, but it may make the playing surface kind of dim.
We'll see. But I wouldn't worry about the heat. It's unlikely it becomes a hot box unless the game occurs during a big heat wave.
