Good review Chas ... and you hit the nail on the head.
This would be useful if there were four different sections ... with some damage .... even one or 2 with sandbags with gaps for rifle positions.
I can see some simple sets useful, where time is saved, but these would be so easy to put together, add in some more varity and fit it your own base, than have to build around them.
I think you were too generous, even, with 65%.