It will still break everything in SketchUp that ceased functioning as intended when upgrading to Yosemite. That being said, we aren’t tracking any big crashing issues at this point and it will likely only be an inconvenience for folks who are coming from Yosemite to El Cap. It will also probably change or break the way your software works. It’s never a good idea to jump into a new operating system on the day it’s released as it will only have been mostly tested and may be missing essential drivers for your devices. Let someone more daring, someone who DOESN’T depend on their Mac for their income, make the switch first. I’m here to say… step back, take a deep breath, and wait. You may be tempted to jump out there and get it, there are reported performance enhancements and it’ll make your Mac work better with your iWatch. Today (September 30th) is the launch day for El Capitan (OS X 10.11) which is a free upgrade for most Mac users.