Have conducted RF chamber testing on many LNBF samples and competitor units during product development. Never released this data as it was for optimizing products which I was involved with developing and not for marketing against competitor products.
It was obvious that some brands and models consistently provided poor performance, noise spikes, etc., while others excelled with higher SNR levels, minimal conversion and amplification artifacts. When these same products were compared in real word tests , the results were similar to the controlled RF space testing.
Yes, system components and install variables will affect performance (reflector efficiency, FD, FL, etc). With that said, all LNBFs come to the table with performance advantages and handicaps.