Not a fan of willingly getting my DNA profiled on principal.
Now let's face it I'm a law abiding citizen, but too many of these DNA firms give up the DNA to the government at the drop of a hat (en masse).
Granted that's been used to find some killers, but somehow a mass grab of DNA meant for Genealogy or Insurance er whatever seems too close to the line of self-incrimination for me personal tastes.
Buring gps based trackers in the bike seems like a better method (and would allow on the option of personally adjusting the attitude of the thief -- not that I would ever recommend such a thing mind you.)