If I add raised wingtips to one of my RC planes, they decrease significantly the aileron authority, meanwhile improving the dihedral effect and the self-stabilizing tendency. But for maneuvrability, it's not as good. If I add an autopilot, like Ardupilot, the raised wingtips will make harder for the autopilot to instantly correct the levelling when passing throught turbulence, because the effect of the ailerons is dampened by the self-levelling tendency. Basically, the ailerons have to fight not only to change the attitude of the wing, but against it's tendency to rotate by itself, that might not act in the right direction when flying through turbulent air.

If I add dropped wingtips, they improve lift (the same wing is capable to carry more weight) and they increase greatly aileron authority, while decreasing passive auto-levelling. The plane becomes harder to fly manually, but for the autopilot the effect is good, because the smallest deflection of the ailerons will have a big effect. The autopilot is capable to correct instantly the horizontal attitude of the wing, by moving the ailerons very fast, and in minute increments. The plane will look like it's flying on rails, even when it passes through turbulence. And the lower the altitude, the greater the turbulences, because the wind is moving over ground obstacles and it's not flowing laminary. When the wind is strong and there are bushes and trees on the terrain, the turbulences can be so great, that a RC model can become impossible to fly low if it doesn't have some sort of electronic self-levelling device.

The conclusion is that, for a plane that has to fly low, dropped wingtips and an active self-levelling device are the best combination.