I've had the Band 2 for a year and wear it every day unless I accidentally leave it on the charger when I leave for work. The original one lasted about 6 months before I started having battery connection issues, and the replacement with the later lot number has been problem free for the 6 months except for the accident described below.
I was hanging security cameras at a friend's house when, due to poor ladder safety, I fell about 3 feet and landed in his shrubbery. The rubber strap on my Band received a significant scratch in the same area where most people have reported the tearing, but as bad as the scratch looked, it still did not expose any wiring and has not torn any more in the past month since this incident. Just as an extra precaution, I have filled this scratch with some vinyl/rubber adhesive in hopes that it will prevent the damage progressing.
In my experience these straps seem pretty durable outside of this accidental abuse, but again the original Band 2 I had for the first 6 months never had any tearing issues either. Maybe I just generally treat my Band more carefully than others?