The smaller bubbles in nitrogen tend to soften the sharper flavors in a beer, as well as hide the more subtle flavors. So much of what makes many Belgian beers distinctive is actually the high level of carbonic acid that is associated with CO2. If you decrease that, then you get a completely different beer.
There's nothing stopping you from giving it a try, though! It only takes one expensive keg of Chimay to attempt the heretofore unknown.