I'm brewing with Wyeast's West Yorkshire Ale yeast, which has a documented alcohol tolerance of 9%.
I'd like to push that boundary by brewing an 8.5% ale and wonder what to expect. Common sense says that this constitutes stressing the yeast, so one would expect the normal things that go along with that, like under-attenuation, stuck fermentations, increased esters.
For the sake of argument, let's just assume that the beer will be well-pitched and well-aerated, to give the brave boys the best chance.
Does anyone have personal experience with pushing yeast to their limit?
UPDATE
The beer I ended up making was not near the alcohol tolerance, nor could it have been, but I still ended up learning something.
The beer (1.064) fermented out to 1.020 with West Yorkshire yeast (6% ABV) and 1.013 with Nottingham Dry yeast (7% ABV). The Nottingham is much better-tasting and clearer to boot. I still love the Timothy Taylor yeast for its flavors, but it would seem that sticking to lower gravity beers is best with this yeast.