I hit a big bump today, and one of the latches popped. The other bag was locked..... but I had just taken off my denim jacket and tossed it in the right side bag.
The bag didn't fly open or anything.... just popped the latch.
Lessen learned...... I'm keeping them locked from now on.
I've never had one open in 60000 miles of riding all types of roads, just make sure safety strap is folded in properly, sometimes it will stay under lid edge and then latch will not close tight