Thanks for your post, Mike! I've DVRs in my class private data, and your idea was just the trick to visualizing what I needed.
A few other notes in case they're helpful:
Clear or handle run-time errors within the probe, especially if you're probing a wire in a loop
The probe window in 2013 seems like it's bounded in size, so use tab controls to keep the window size small
Hide the required custom probe interface to gain additional real estate in the probe window
Dynamic dispatch VIs must be shared reentrancy, so there probably shouldn't be state in the probe