It was always my belief that if you are issued an instruction by air traffic control, and have been positively identified, then they are primarily responsible for terrain separation. My previous post was perhaps poorly written - it's very bad SA if you blindy accept what ATC tell you without question. When operating near mountains or other obstacles I would always refer to MSA and reject any clearance I was not happy with, regardless of who is TECHNICALLY responsible.
Bookworm - thanks for that reference, I was beginning to doubt myself!
Horgy