Earvana - similar principle of minute/small scale length changes-seem to have a good rep, with their nuts being reasonably priced ($25) - plus if you screw up instalation(sp) you have the option of being able to buy a either the top or bottom part separately.
http://www.earvana.com/ - they give fairly detailed instructions for fiiting as well.
I must say i have not tried either but may go for an earvana nut on my tele copy later in the year as she needs a new one anyway.
Accuracy,you say? hmm interesting concept..
