Designing Levels in 3DS Max?

The project I'm working on consists almost entirely of interior scenes (it's basically on a space ship). Most of the static structures (walls, staircases, etc) have more or less been built within 3DS Max, and I originally intended on just separating that into different rooms and streaming them as levels, then decorating them with reusable prefabs.

However, since a large portion of the static scenes are more or less iterations of each other, I'm wondering if I should reconsider using unique rooms (some of which are quite large), and deconstruct those into prefabs and build the scenes within Unity?

For instance, rather than having ten large rooms I import directly from 3DSM as a level, I would import some 20 or 30 prefabs for floors, ceilings, walls, etc, and just spend the time building the levels from those tiles. Which would not be difficult to do, though maybe time consuming. I would prefer to do it via the prefab, as I feel like it would let me have more variance with the materials, as well as more interactivity with the environment, and I could add significantly more detail to a few tiles that make everything than adding it to the individual scenes. At least, I could do it easier anyway.

My primary concern is that doing so would cause too many draw calls, and would significantly increase total tri count (since, rather than having a few large polygons for a floor with repeated textures, I would have some 100 iterations of prefabs). And I don't know enough about the backend to really make an educated determination on whether or not that would be a significant enough drawback to make it a bad idea.

I mean, obviously either way I can accomplish what I want, but perhaps someone can drop a knowledge bomb on me about how significant adding draw calls vs. rendering large models is?