CCC is not working due to compatibility.. same as Little Snitch :\
Which version did you try? V4.x works with El Capitan and Yosemite. V3.5x and earlier supposedly do not work with them. The first thing I did before upgrading to El Capitan was to purchase an upgrade license for CCC from 3.5x to 4.x. It appears to work fine here.
Talked to Bombich-Carbon Copy Cloner yesterday. It is fully compatible with El Capitan.
I'm guessing he used an earlier version. Therein lies the rub with much of the software issues. Many updated packages work with El Capitan but older versions do not. Others have not been updated and may never be updated and many of the updates aren't free. So while El Capitan itself may be "free" the costs associated with getting updated versions of software to work with it can be VERY expensive in some cases with professional type software that as a consumer you bought once for the awesome features, but don't want to have to buy again, even at upgrade prices since you don't need the newer features and aren't making money from it. You are then really just paying to keep it working with that "free" OS upgrade.
I want Metal for future gaming, etc. since that will actually make the most of out my 2012 GPU (Aspyr has said they may very well go back and update older releases that need a lot of GPU power at some point) and certainly most future games will make good use of it and may even REQUIRE it at some point very soon. But most other OS X "features" since Mavericks are pure fluff to me (I don't have an iPhone so I don't care about continuity, etc.) The extra pane in Notifications for the weather, calculator etc. are "nice" but I can live without them. I like "dark mode" but I hate the stoplight "flat" buttons compared to the "gem" like ones in Mavericks. So it's a bit of a wash.
El Capitan "feels" about the same as Mavericks so far, but (ancient) XBench tells me otherwise, assuming the tests still mean something. It says half the tests are slower, some a LOT slower (my RAID hard drive does 190MB/sec at most now; it did 286MB/sec under Mavericks and damn near 300MB/sec under Mountain Lion with the same tests. OpenGL is similar or slightly faster, but Quartz tests are considerably slower. Some of the user interface tests are slower and I figured with metal in the main GUI they would be faster, but perhaps they use outdated calls or something. It's hard to tell. My animations were already smooth in Mavericks here so I can't see any visible difference. Boot times suck so I kind of believe the slower hard drive tests. I think they figure you will have SSD by now, but that isn't always true (some of us need a LOT of hard drive space and a 200 or 500GB hard drive isn't going to cut it. I have 5TB here and I'm running out of space).
