RE: Brillelli 46cc
On our Christen Eagle the rubber bushings lasted a season. I would replace them every season for sure. I think they are cheep and the vibration isolation is worth it IMO. The Dubro mounbts are also easier to work with when mounting the 46 and I believe they are stronger than the H9 mounts, but either work well. I just know after running th Dubro mounts on the CE and feeling very little vibration in the plane from the engine, I was sold on them.