For the last several brews I've been using Go-ferm to improve the health of yeast before pitching it. I mostly use dry yeasts and add it to the starter (really just hydrating, not multiplying). Since I've started using it, my fermentations have been nothing short of spectacular in the rate they go at. You'll want to keep your primary in a place 5-6 degrees less than the target temp because the activity is so high a fair amount of heat is generated. If you have problems with slow or stuck fermentations I would highly recommend trying it.