There's no better place to put them if your goal is redundancy with lots of small props. Puller props are generally more efficient because they're not in the wa

There's no better place to put them if your goal is redundancy with lots of small props. Puller props are generally more efficient because they're not in the wake of the wing, but it's a tradeoff and you can Google as for the pros/cons of push vs. pull props. The larger tip props are really interesting. Larger, slower rotors are more efficient. Putting them far outboard puts them in the least-disturbed flow while knocking out the tip vortices. This is only possible with lightweight electric motors vs. shrouded turbines, otherwise the wing/wing box would be quite heavy to support such a long moment arm.