Multiple HMDs in the same room setup, acheiving identical configs?

Yesterday I setup two Vives for the first time in the same playspace and began developing a networked test game.

Before I got too far ahead of myself i was wondering how similar two room setups would be on two different PCs where both were calibrated in the same room by the same person?

Would both have a good linear relationship when compared to each other? In other words, if two ppl share the same playspace then would all player's hands meet at the same point in all four corners and center of the room?

Sometimes I notice after a room setup the floor is a little uneven and my controller can go under the ground in one corner of my room, while above the ground in another. would differences in floor level/grade between two roomscale setups cause unforeseen issues?

I have tried my best to do both room setups back to back, and in an identical way. Which so far has not caused a problem, but my playspace is small. And at some point I intend to use LightHouse 2.0 in a 30x30 space, would the larger area cause greater error (if any)? And when calibrating large areas, Is there anything I should consider to always obtain identical roomscale configurations?