Using Virtual Partner on Garmin 500 (or any other Garmin)

I've never used the virtual partner feature, but it sounds like something cool to use for my HIM coming up.  I did the race last year, and have the bike course saved in a garmin file, ready to load back to my 500.  I won't have a chance to test the course until race day as I need to travel.

I would still race by my normal metrics, but over the course of 56 miles, I think it would be cool to see how I was doing compared to last year.

One thing I read though is that once you start the virtual partner, you can't turn it off.  So I was wondering if there is anything I should be concerned about.  It says that if you go off course, a message will be displayed.  The last thing I want though is a "off course" message every 2 minutes that I can't turn off.  (ETA: I confirmed that the bike course is exactly the same as last year)

I'm guessing it would work well since the auto lap by position has worked well for me, but just wanted to hear what others may have experienced. 

I'll probably test this out with a short loop around my neighborhood.