I have the 705 (5 years) and it is really excellent. Good battery life, great screen resolution, accurate. Turn by turn is prompts and on a bike not that useful. But the 705 can be used in car mode when traveling ... as useful as any other GPS. They are so accurate that if you pass another rider you can get prompted that you are off course.

Other courses/cue sheets is a 3 or 4 step process. Create a map, save it, upload it to the Garmin and then tell it you want to use the course. I use Mapmyride. Lots use Biketoaster.

The mapping feature is what is most helpful if you do rides outside your area. If you want to ensure you you know where you are, on course, or where you what to go. imo