Some of the "advantages" each camera holds over the other are minuscule and don't matter.
The advantage of the SX260 is size and weight.
It has a 10% larger screen.
The advantages of the SX40 are the much longer zoom, and it's support for an external flash so you can do bounce flash.
It's a half f-stop faster.

It has a 24mm equivalent focal length instead of a 25 mm focal length.

Now if it had a 20 or 21mm equivalent focal length...
I'm curious as to how a camera can shoot 10.3 fps when the shutter lag is 350ms, which is over a third of a second.