Well I have plenty of real world experience and have used a number of LNA's at many locations and have had good luck with almost every configuration. Again, some common sense and picking the proper product is part of the equation. Some cases could be problematic for a wideband LNA, these are often the exception.
I would say I am located in a very harsh environment being just a few miles from Washington, DC with not only MANY Public Safety systems but probably more Federal Government systems then you will find almost anywhere else in the US.
I have multiple cell towers between 1-3 miles from my antenna and the majority of the DC market TV and FM broadcast towers are within 4-7 miles of my location. I have a flight path that often puts commercial airline traffic directly over my house, but the normal flight path is as close as 1 mile from my house.
I would say few of the members here are in a worse environment than I am, but some are and they may have some challenges with trying to use a LNA. But as I stated above, there is also some planning that goes into what LNA is chosen and why. There are plenty of Pre-Amps, not all are created equally.
Like anything, until you try a set up, you may not know how well it will perform, in some cases you will have some challenges, but most challenges can be addressed as needed. Although far from ideal, the LNA can even be put mid coax path or right at the receiver, however, if the LNA is put right at the receiver, the radios attenuator or an input attenuator may be required.
While you may have 40 years of experience, also understand what you may have worked with even 10-20 years ago is not likely as robust and of a low noise as some of the more reasonable options are available today.
What I am trying to do is OPEN up some people minds here, not to listen to all the negativity and consider using a quality LNA and they will find for themselves they are missing a lot of signals in their area. In only a small number of cases, I would expect problems and often it takes some trail and error playing around until things are optimized. I had a severe FM Broadcast problem I had to address and probably tried half a dozen FM Broadcast filters until I found one that worked very well.
I am offering solutions that I spent a fair amount of my time and money fine tuning and I am sharing what I have with other members of the community.
So you can live with what you have, but until you try what I have suggested, you are the one missing out.