i have used two paralegals for two different driving infractions, though not as serious as yours, so here is my advice.
stay away from the corporations like pointts. what they do is quote you a set price for the defence, what they do is go to the prosectuter and simply try to get the speed reduced, if you were caught doing 121 in a 50 pointts would try to get it as 100 in a 50 and tell you to be happy with it. they deal with many clients and the fastest way to deal with anything is settle it before it goes to court. I hired pointts for a ticket where i was caught doing 124 in a 100 zone and the pointts guy did not get it reduced at all, and i was convicted in court. i paid $350 for nothing. for another incident i hired a local paralegal who charges by the hour. he went through my case and tried to find a way to win, instead of just getting a reduced charge. since he was charging by the hour, he didnt mind doing lots of work on my case as he was getting paid for it. i ended up getting off that charge all together. be prepared to spend about $650 for your representation, but it is probably worth it. write down right now everything you can remember from the incident, no matter how small a detail it is. ex. was there a construction site near by? any high tension wires? stuff like that.
if you go to court to try and fight the ticket, you are looking at an all or nothing situation. you either get off or get nailed for the 121. you have to decide if you would be better pleading guilty to a 100 in a 50, or risking get nailed for the 121 but having a chance to get off all together.
one other quick thing. after you set a trial date, if the date is a long ways away like more than a year, your constitutional rights may be infringed, the right to a speedy trial. there is a form you can fill out and send in claiming this, but if you have representation, they will do this for you.
good luck with this, keep us updated.