I’ve had a couple of issues with my E13 XCX BB mount:
* Initially I didn’t crank up the BB cup tight enough so when I accidentally clumped it with my 5-10s, it rotated around and loosened the cup in the process – a nuisance when half way around the ride. Lesson learned – tighten the cup quite a lot.
* A chain link broke on Sunday and the broken link jammed in the cage as I was pedaling, dragging the device around the BB. After freeing the chain, I managed to tap it back into position with a rock.
I imagine these rotation issues are solved by having the tabs on your frame, but then being flimsy plastic, the devices probably just snap off instead.