I just bought one a month or so ago to speed up carbonating soda water. I always keep a 5 gallon keg of soda water on tap and got tired of having to wait for a new keg to fully carbonate when the old one ran out since I drink a lot of soda water during the week. I read that you are supposed to slowly ramp up the carbonation pressure over time, but do not understand why. I just fill my keg with water, put on the lid, put it in my keezer, attach the CO2 set to 35 psi for soda water and let it go overnight. I have carbonated soda water by the next day. I did the same with Kombucha and it worked just fine at 12 psi in a 2 1/2 gallon keg.
I have not tried it with beer yet and wonder if this would also work overnight if set at an appropriate psi like 12, but have not tried it with beer yet. No need. I have too many full kegs waiting to be tapped since I stopped drinking beer during the week and now have the luxury using the set and forget method for beer kegs.