Hi hgroth ....
You are just one of many searching for the 'Holy Grail' of LNB's ..
Many will have their own opinion as to which is best ..
I personally have not yet tested an Inverto Black Ultra ...as they are as rare as hens teeth in the UK ..
..but I believe these lnbs ...in single twin and quad form to be certainly 'amongst' the best ...if not 'the best' ...for fringe reception..
rgds
VS