OK, so here you are! Sorry about the crappy lighting. You can see it's pretty much as I posted above: Micromaster and Smallest Transformers car alt-modes are dead on scale to each other, while the Smallest Seekers are in a slightly larger scale than most Micromaster airplanes.
Check out the following links for a good idea of how Smallest Transformers look on both Metroplex
(with Reprolabels upgrade set)and Trypticon
(with Reprolabels upgrade set). A clue: it's absolutely awesome! Both Micromasters and Smallest Transformers were just MADE to fit in with the bases. I too can't wait to see how they'll look on Fortress Maximus!