I didn't expect Die Cast Metal - I don't think MP Prime is any part metal either. Oh - maybe the chest panels in the front of the cab that open for the Matrix of Leadership. But most of him's plastic.
If the guy didn't extend Starscream's legs or something while transforming him, that might be an issue with the height. I could have sworn I saw a picture of the two MPE together and Starscream was the same height as Prime (about 12").
We'll see when it arrives I guess. I have not yet been charged nor e-mailed that it is shipping. The website said "In-Stock" though - and I got a confirmation e-mail about my order. Since then, that's been it.
I probably ordered it about a week ago - immediately after you provided me with a couple links to buy Starscream from. (I still give my thanks).