I am in the process of a build right now and am wondering if a knock sensor with a display would be a nice safety margin addition to the car??

 

If you can log it sure. otherwise the pfc/datalogit already log and display knock. As most other stand alones do.. My knock sensor didn't even work correctly for a long time, if you run a conservative tune and get it dialed in I don't see a reason to monitor knock too closely.