Wyeast versus S-04

So I have a recipe to make a Sweet Stout and it calls for Wyeast (Whitbread) 1099.

Yeast I bought looks bad or very slow to start in starter...and I want to brew this Saturday....so it looks like the 1099 will not be ready or any good.

I have S-04 on hand in fridge and I have seen several posts that say it is same (or equal) to Wyeast 1099.

Is this true? Should this give me same or similar beer?

Also, got to thinking, what is the benefit of liquid yeast over dry? For liquid you need to do a starter.....and liquid costs more. For a dry yeast no starter needed and it is cheaper .....so why is liquid yeast seem to be preferred????

Variety. White Labs and Wyeast produce a lot of variety in their lines of liquid yeasts. Companies like Fermentis and Danstar (Lallemand) only produce a few limited selections of dried yeasts. Other than that, both dry and liquid yeasts can produce good quality beers provided you pitch the proper amount and re-hydrate the dried yeast.

Use the s-04. You aren't looking for much yeast character in a sweet stout anyways.

S-04 will make a beer that tastes generically british ale-y. If you want a really true character, a very healthy pitch of a liquid culture will give better results.

S-04 is a great ale yeast. I have done some side by side on Ales and Lagers using dry of Wyeast. One ales, dry is fine and very difficult to taste or see any difference between the 2 except cost. Rauchbier lager is also fine with a dry lager yeast. I would not use a dry yeast on any other lager as you cannot hide in a lager.

Just a note, in my experience 1099 doesn't bubble all that much but certainly does ferment just fine. Make sure to take a gravity reading to judge how it's going.