I've been touring for close to a years with this cab and it's very nice. I play 7 shows a week in a studio setup and the band leader has an open talkback mic all trough the show. Now I can crank up my badger 30 real loud and none of it will spill on the band leader's talkback or the vocals.
It's not 100% silent. It cut about 30db wich is more than enough for me because I still want to feel some vibrations when I play but know that it will produce vibrations. It's very well built and sounds great! I've tried
many other solutions out there including building my own amp box and the SilentSister is definitly the pro solution. I've tried to block the pressure relief hole to see how it would sound and there's no doubt now that it's what makes Rivera's Iso Cab sound better than all the others. It does not sound boxy at all. For recording, this is also fantastic because for all of you guitar players out there who are making home recordings well you won't have to worry about a car driving by or the air conditioning getting picked up by the mic or anything else you can think of.
Mine is loaded with a Celestion G12H and sound great and I'm even thinking getting a second one with the new Celestion Creambacks to do some real nice stereo effects!