Both batches. The first batch though I just absentmindedly threw in the yeast still dry. Realized my mistake when I checked on it an hour later and the dough hadn't risen at all.
no proofing. Obviously not a big deal to do, but sometimes forgotten.
more activity per gram
lasts longer
consistency, I know that X amount of IDY at this dough temperature, will give Y rise, in Z time.
versatility, you can make a batter as a pre-ferment for an emergency dough, or you can do a long cold ferment. You can do this with other yeasts or sourdough starter obviously. Using IDY in these cases reduces variables.
Sorry I'm trying, slowly, to put together a post about the different commercially available yeasts. I think IDY is the best, and I do not see a trade off in flavor.