General rule of thumb is to go to traffic school. My understanding is once you contest the citation, you lose the right to have the citation masked from your driving record should you lose. However, you can always ask, "if I am found guilty, will I retain my right to attend traffic school to keep this from going on my record?".
If you do a TBWD and say you were doing 55, while the officer says you were doing 75, the judge always sides with the police officer. This means that you are dealing with a biased judge and should be able to get the ticket thrown out on that basis. I don't know how you'd do this, as I can't imagine the following question would work: "Your honor, if I say I was doing 55 and the officer says I was doing 75, who would you side with?".

