For some reason, I only got around to trying out the Optimus-Jetfire combo in the last few days.

It's certainly an impressive piece, and everything holds together well. I even like the absurdity of the gigantic cannon formed by Jetfire's upper torso. Sure, it's not screen-accurate, but that doesn't matter. It's massive and awesome-looking, and that's what matters.

Something to note is that Silverbolt's pictures above are a 'fan mode', where Jetfire's spine is folded back and the back panels are swung out. I kind of like this configuration, as there isn't a giant block hanging over Optimus's head and the splayed-out back panels approximate the large panels that were actually seen on Optimus's back in the movie, but for the sake of showing the figure as correctly transformed, here is the stock configuration: