I want to up grade my c550 to something with lane assist

Look at the 7X5T series. My daughter has the 755T as her car has built-in bluetooth. If you want the bluetooth feature then it's the 765T. She has only had it for less than a week but she hasn't complained about any problems. She got it at Amazon.com. The price was comparable with other stores.

I have a c550 and recently picked up a 765, love them both. The wife has been bugging me to get another unit so she could have the 550 in her car.
Lane assist is awesome and an immense help navigating some of the confusing multilane highways we drive on. Compare units that have lane assist and go with the one that has the other options you need/like, such as bluetooth etc.

My son has a 265wt but no lane assist and lacks mp3 ability. Another C note and ya got a 765!