One concern with dual battery mounts is that straps are secure when only using one. First time I attempted to launch with both packs (all 8) mounted - no success, fickle breezes. So I decided to dismount the top pack to make the launch easier. Left the strap for the top set loos and of course it caught a prop. Of the four blades between the two top propellers the blade that was already chipped took the hit. It cracked.
Fortunately I’ve repaired it. I’ve also ordered 2 more props. Could only find the DFDL branded ones on aliexpress.