I bought mine a few months ago and found that the lid gasket seals well. Just make sure that gasket is pressed firmly into place in the channel on the lid all the way around after cleaning. I connected the blowoff tube to a CO2 Harvester with 1/2 gallon jars, and it all worked fine when I cold-crashed from 65F to 39F. The Starsan in the 2nd jar of the Harvester was drawn back into the first jar (as it's supposed to do), without any apparent loss of suction.
One thing to watch for--the position of the dip tube. I had the dip tube pointing downward, and forgot about it on bottling day. When I racked, I got a bunch of trub initially and had to rotate the valve so the dip tube was pointed upward. But that's on me and not a fault of the Brewbucket.
I like mine and will buy a second unit.