Like Costactc, I have both the Invacom TWF-031 LNB and Gibertini feedhorn. Also its LNBF sibling the TWH-031. Both quads.
I now use an Inverto BU. Both give good gain across the spectrum -around 50dB - but comparing signal/noise readings, I found the Invacoms were a little noisier than the BU at the top end of the band. And of course they are much dearer.