The case of
http://forum.tvfool.com/showthread.php?t=2899 is more interesting. The predicted NM for WMC, real CH-5 is only 3.7 dB and, in addition to the 2-edge path, there is some co-channel interference indicated.
The OP is/was using an antenna described as, "about 20 years old and its huge". That leaves us to estimate/guess at the gain and F/B ratio.
The OP reported less than 100% reliable reception of WMC:
http://forum.tvfool.com/showpost.php...2&postcount=13
My 'read' of this situation is, beginning with a NM of less than 4 dB is at best a marginal situation. Such a situation is not hopeless, but calls for realistic expectations to be set, and deserves aggressive or even extreme measures to improve the reliability of reception.
Again, a very useful data point.