So, I just read about the Starfield kit...
http://www.fantasyflightgames.com/edge_news.asp?eidn=4075
And... I'm not sure about it yet. It seems to me like it's going to be more of a pain than it's worth. One bump, and the whole thing shifts.
I've played Mansions of Madness, and they have the same kind of "board." While it's awesome that they are interchangeable, one little bump throws everything off... and that's just a regular, "move-your-piece-2-spaces" kind of game.
I can't imagine playing XWM, where you have to measure, move, then measure again (wash, rinse, and repeat) and NOT destroy the board.
HOWEVER... the idea of inter-changeable tiles sounds like an awesome idea, IF it was done right. I wouldn't mind this idea if there were little nubs to help lock the tiles into place, even if they stuck out a bit at the edges. It kinda makes me want to go to the hardware store and pick up a few pieces of fiberboard to make my OWN inter-changeable mats...
I am going to need a bigger gaming table...