I run TLR springs, no complaints, good springs, and more importantly for me, they don't pop off so much, meaning the spring cup thingy stays in place, and the spring stays in the cup thingy.... I have known ppl, loose the spring cup thingys whilst running...
for conversion of spring rates, see link.... you can use force per unit length for the conversion
http://www.katmarsoftware.com/uconeer.htm