Hi there
"Super tiny" - I didn't look at the file, but the example image doesn't seem to show smaller models than I use at the moment.
I work on a picture with lots of small objects, some of them less then 1 cm in diameter and a few millimeters high. The biggest element is some 15 cms high. I create those things in a separate file, with the material, test-render, and put them in the other file afterwards. Up to now I didn't experience any problem. Didn't create all of them in the actual version, though, but some of them yesterday and today with 26.
Often I shape those things in bigger scale (say 10:1) and make them smaller afterwards. Especially in a really physically based render engine it should make a big difference in make-believe using the accurate measurements of an object. It's about light and the 'virtual lens' of the camera. Working in wrong scales I usually get the 'model feeling'.
Anyway, as I didn't experience the problem, there must be something else strange with the models. Maybe it's just the pivot or so.