grounded27, I am not sure I understand your second paragraph:
"Also terrain avoidance, I can think of many times I have descended through terrain at high altitudes (baro) but were within close enough proximity to the terrain to necessitate it's use above 10k at or possibly faster than 250 kts." Are you saying that there were many times when you could not be sure of terrain clearance just from baro altimeter and position, so needed radalt? Does this mean you flying into a region where the terrain height was not known?