[dubious elise]

Aha, I completely misread your initial post, David!

I thought that you were referring to a massive, pit-area-wide structure that would have multiple floors to accomodate extra teams and work/practice/shop spaces (I think I mentally deleted the 10x10 blurb). This, in and of itself, would be very cool and might allow venues with relatively cramped pit spaces to open up a bit and allow the full 10x10 footprint dimensions, if not more. Obviously, the overall height of the arena and the lighting of each space would be issues to tango with.

As for individual pits, I'd be worried about either having kids fall out of the upper levels or, if you have workspace on the upper level(s), having materials/sparks/nuts and bolts either fall through the floor or hit passers-by. We might have to start telling kids to keep their saftey glasses over their eyes on the field and on their foreheads in the pits.