Wow, that's some theory. As much as there aren't any set rules on Cybertronian biology, I'm not sure how that could happen. Then again, we've seen Megs used as a space bridge and the guys stuck in the Dead Universe pop out of Brainstorm, which was kinda like giving birth...to big robots.
I like the idea, it's different, but I don't sucsribe to the theory. Firstly, Prowl is bigger because pre-Dark Cybertron he was given a new body after an explosion damaged him. The Decepticons rebuilt him, whilst under Bombshell's control, and gave him a bigger body so that he can form part of team Devestator. He's basically had an upgrade from Deluxe to Voyager!
Secondly, I think his mental weirdness is a sort of bleeding effect from the gestalt process. It's telling because he's been getting that foreshadowing nosebleed thing that happens to characters when they're about to get mentally messed up or suffer from a brain disease.
Scrapper's identity, and perhaps his consciousness, was a part of Devestator previously, so there are remnants there. The Constructicons probably don't feel this, like Prowl does, because whilst they were formed into Devestator as part of a singular process by Shockwave, Prowl has been effectively shoe-horned in. Devestator's initial creation involved all 6 Constructicons with their personalities being fused in a stable way as to create a single identity (and a sane one at that, unlike the mess that is Monstructor). Prowl is a usurper who has taken Scrapper's space, so when Devestator is formed there's probably a two way process going on where Prowl's consciousness is going in, but Scrapper's is bleeding back.
I do hope that makes sense...