What I understand is, that it really depends on what Radiotor you use. The're some that will perform better with high pressure and some will perform better with lower pressure. It depends of the actual space between the fins in the Radiotor.
I don't know if I mentioned it allready, but I am really sorry if my English isn't correct, since I am Swiss
It is easily comprehensible, it's a lot better than most people online these days.