K52,
As a VFR pilot I cannot comment on IFR procedures but, as a scientist, I believe that anyone who thinks it is safe to fly 25 passengers into such a small window (500'?) between SALT and the FORECAST 4 deg isotherm has a highly questionable attitude to flight safety. This seems to apply to you, the AM,s, and most of the SH force. John Wilkinson and Peter Crawford (ex S/C Odiham, among ,many others including possibly the Chinook pilots, say they could not safely climb above SALT. With so many eminent helicopter pilots disagreeing, the least any right minded person could concede is that there must be DOUBT.
I would be interested to know what tolerance one should place on a forecast value. Even if you were in a position to locally measure the isotherm level you would have to state a tolerance based on the equipment used and the number of measurements you made. I would not base my life an a measurement tolerance better than 500' let alone a forecast. As a VFR pilot I only have to think about how many times I am frustrated by cloud base forecasts to know that.
I will leave others more qualified than I to comment on your continuing habit of throwing new angles into this debate, that of the number of captains around.