I just bought the Gibraltar hi hat seat and washer set and it's made my Sabian B8's brighter, have more sustain and makes my hits more articulate. With the standard felt washers, seat and washers, I feel it muted my hats too much. They also rock back n forth a lot easier as well.
As a note I break the washers in when I remember to. I compress them by pressing down on the pedal and then when I clean off my hats, like get all the wood chips out from inside the bell of the lower hat and give them a hit of Groove Juice I will squeeze the washers between my fingers to make them a bit more soft. I find they are a bit too hard to start with but overall like them a lot.