i use fishing trace wire, the plastic outer is great as after you've crimped it you twist the end around the line a bit, then wave a lighter under it to melt it together.
high pound strenght wire is ok, but think of it this way ( what with the AMA trying to save every blade of grass ) what do you want to break? servo grears, horns? or the wire?? personaly i use wire rated just above my servos pulling power ( x1.5 at the most ). this means you can deal with blow back ok, but any hard crunch should snap the line before anything else goes..
thats my theory anyway.