My HD is partitioned into two. One has the OS I normally use (images etc are stored on an external HD). I use the second partition to experiment with.
Earlier today I cloned my 'main' OS partition to the second partition...then upgraded it to El Capitan...which I am using at the moment to see how it goes.
My feeling is everything is working a lot faster. Anyone else using El Capitan...and if so, any observations?