How exactly did the Reliant "rip off" the original Enterprise by inverting it?
Yes, the Akira does have some structural similarities to the configuration on the Miranda, but that hardly makes it a rip-off. The Nebula is more similar. It's like claiming the F-15 is a rip-off of the F-14 because they have many design similarities. Or the F-18.
And the Akira has been onscreen far longer than the few minutes in FC. It made quite a few appearances on DS9, and one appearance on VOY.
I'm inclined to agree with Forbin on this. The only other designs in canon that look so close are the original Enterprise and the movie refit, and there it's intentional. The Akira was chosen as a template for the NX because Berman thought it'd be kewl, just like it was "kewl" to add the Borg on ENT.

And the Akira has been onscreen far longer than the few minutes in FC. It made quite a few appearances on DS9, and one appearance on VOY.
I'm inclined to agree with Forbin on this. The only other designs in canon that look so close are the original Enterprise and the movie refit, and there it's intentional. The Akira was chosen as a template for the NX because Berman thought it'd be kewl, just like it was "kewl" to add the Borg on ENT.