Decided to upgrade my iMac (27 late 2013, 32 gig ram, 1 tb HDD, and three external USB disks 2 gig, 2gig, and 1.5 gig, all connected to two additional samsung monitors and a Fax, Scanner and copier and printer the HP office 6100), computer to El Capitan? Afterwards, I started having problems with my USB Bose Companion 5 speakers, they suddenly lost the sound, and I had to restart the iMac 3-4 times a day. Then, when I opened mail, the memory allocated to it went from 7 gigs, to 25 gigs and all of my 32 gigs went into the mail app and the computer just froze from the slowness due to the kernel and the mail programs eating up all of my memory. Tried various fixes that i found on the web, nothing worked for the usb sound problem, and then also the mail recommendations none of them worked. The machine would reboot to a practical stand still, so y decided to go back to Yosemite, hoping that one day El Capiturd will grow up to El Capitan. I personally don't see El Capitan as faster. Still riddled with bugs and problems, a total first for Me. Very worried and disappointed.