MP Optimus is not the same as the one from 5 years ago, it's an all-new figure that's got different stuff going on, an all-new sculpt that's less simplistic and features more of the character than the truck (and yet the truck mode also looks better). It's also a shorter scale though. But it has Roller, where the original MP trailer didn't. I bought the TRU exclusive preorder after seeing Chaddy's import version for only a few minutes.
It doesn't matter, you won't be able to find 'em anyway.