After only my 2nd batch I was annoyed with how little wort I got from my partial boil, especially when steeping grains. I would start with about 3.5 to 4 gallons in a five gallon pot (ceramic on steel canning pot) and end up losing over a gallon from evaporation and foaming and absorption in grains.
I bought some Fermcaps (stored in cooler with yeast if you go looking for it) yesterday and our works GREAT! I filled my pot to the rim in anticipation of losing over a gallon like before. No foaming, no boil overs. My finished wort still had 4 gallons left so I only had to top up with a 1 gallon jug off mineral water.
Well worth a few bucks. And now when I go to a bigger pot, I can stick with a cheaper thirty quart versus getting a forty or bigger just to avoid boil overs.
Three cheers for Fermcaps!