Well I updated recently. I haven't any big problems. Everything is working like before. However you can get problems with homebrew because of permissions. But there are easy fixes. If you have /usr/local just change the permissions.

If you were installing gems with sudo, you will get some trouble. The gems will not work anymore. But you shouldn't install gems with sudo no matter what. Change the path to your home folder and you're fine.

Couldn't see any performance improvement. Photoshop CS6 seems pretty slow. But I don't really mind because I switched to sketch a while ago.

Well I'm a Front-End developer and my everyday software involves Photoshop, Illustrator, Sublime Text 3, Prepros, sometimes Github, Mamp Pro. I've upgraded to El Capitan and the couple of days I've been with it it hasn't improved that much in fact it kind of downgraded in transition and scroll "effects" in Sublime and Adobe, basically it slows down sometimes but just sometimes, specially when having two desktops and with a lot of software open. I hope this help you. I must say that I use a 27 inch iMac (3.2GHz Intel Core i5), 8 gb RAM and NVIDIA GeForce GT 755M 1024MB

I'm waiting a couple of months, the last two upgrades broke certain things on my dev environment, it killed maven and I had to switch to homebrew's maven and one of the other upgrades did something strange to Java which meant I had to spend time getting JDK to work properly again - both times were during busy times when time-wise I couldn't really afford to spend time on those kind of things. If you don't have any giant projects that will be affected if your dev environment stops working, go for it!

There is a great performance in graphics. I use two 24" 1080p monitors plus the 13" retina display of the macbook pro early 2014. And before El Capitan, changing spaces and triggering exposé was slow and laggy, now it feels smoother than I thought it could ever get.

Just use the Tux :P (Disclaimer: I don't have a Mac and I will probably never have one cause I only trust my Linux machine)