In terms of the MFJ there are times it will help and times it will make things worse and that is exactly why people's comment about it vary. It does have the benefit of pre-selection (although broad in nature rather than frequency-specific) and variable gain and those factors may help. But it also may set a noise floor that is higher than that in your radio and in that case it may make reception worse. And there are other variables which can make it better or worse than your SAT 800 wth its own antenna or your loop that are hard to predict so once again we come back (unfortunately) to trial and error. It is very likely it may help on some signals and not on others so if the cost is not an obstacle it could be considered to be another tool in the toolbox to use when it helps.
As for the BHI I have not had the pleasure of using one of those but the comments are very favorable on it. I know from experience in general that DSP processing (the kind you are talking about here, not general DSP as used in a radio) can do remarkable things in terms of noise reduction and my intuition is that it may be a remarkable line of products, but again, I have no personal experience with their things. They do look nice though.
Jay
