I believe a bubbler is a very cheap, simple, and easy component that provides several benefits. I would say that main benefit is filtering the HHO and vapor that comes out of your cell/generator. Many say that the electrolyte will stay in the solution, but this has been found out to be false. A bubbler is a good way to make sure that the electrolyte doesn't make it to your engine which can be very harmful depending on what you're using.
Personally, I would never run HHO without a bubbler.
Give a man a match, and he’ll be warm for a minute, but set him on fire, and he’ll be warm for the rest of his life.
2000 Pontiac Grand Prix GTP 3.8L SII S/C'd
15%-20% MPG increase at 1.5 Amps
2000 Jeep Grand Cherokee Limited 4.7L V8
No gains.