I can't answer your question really well in terms of the Belgian yeast specifically, but I had a couple of experiments that I did with my One-Hopper Wheat recipe, which is based somewhat on a Gumballhead clone. I did one batch using Safbrew WB-06 and found that it was way too estery and phenolic for my tastes. Of course, I also hosed up the dry hopping, so I didn't get nearly the results I wanted. Then I did another batch and split it, using Wyeast American Wheat in half and Nottingham dry in the other. Finally, I did another batch with a friend, and he used California Lager Wyeast while I used Bavarian Weizen. Long story short, I found that the esters and phenols, and accompanying aromas, did not really fade over time. Now, after drinking a couple, I didn't mind what I considered to be undesirable flavors quite as much. I'm only talking about a period of several weeks though.